diff --git a/CMakeLists.txt b/CMakeLists.txt
index 06dcd3da3..ec620b7e2 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,7 @@ project(cmark-gfm)
 set(PROJECT_VERSION_MAJOR 0)
 set(PROJECT_VERSION_MINOR 29)
 set(PROJECT_VERSION_PATCH 0)
-set(PROJECT_VERSION_GFM 6)
+set(PROJECT_VERSION_GFM 11)
 set(PROJECT_VERSION ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}.gfm.${PROJECT_VERSION_GFM})
 
 include("FindAsan.cmake")
diff --git a/api_test/main.c b/api_test/main.c
index efed0fb60..e950451ba 100644
--- a/api_test/main.c
+++ b/api_test/main.c
@@ -1575,6 +1575,7 @@ int main() {
   int retval;
   test_batch_runner *runner = test_batch_runner_new();
 
+  cmark_enable_safety_checks(true);
   version(runner);
   constructor(runner);
   accessors(runner);
diff --git a/changelog.txt b/changelog.txt
index 4cc5c58ec..848e71029 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -1,3 +1,44 @@
+[0.29.0.gfm.11]
+
+  * Improved fixes for polynomial time complexity issues per
+  https://github.com/github/cmark-gfm/security/advisories/GHSA-66g8-4hjf-77xh
+  (#323, #324)
+  * Added fuzzing target for bracketed patterns (#318)
+  * Fixed bug in list numbering introduced in
+  763587e8775350b8cb4a2aa0f4cec3685aa96e8b (#322) which caused list numbers
+  to increment by 2
+  * Fixed strict prototype clang warning (#310)
+  * Fixed regression test (#312)
+  * Added additional output formats to quadratic fuzzer (#327)
+  * Fixed buffer overflow in fuzzing harness (#326)
+  
+  Note: these changes may lead to minor changes in expected output on plaintext 
+  rendering of list items. Notably, blank lines may no longer delineate the start 
+  of a list when rendering to plaintext due to changes in how the tight list status 
+  is calculated.
+  
+[0.29.0.gfm.10]
+
+  * Fixed polynomial time complexity issue per
+  https://github.com/github/cmark-gfm/security/advisories/GHSA-r8vr-c48j-fcc5
+  * Fixed polynomial time complexity issues per
+  https://github.com/github/cmark-gfm/security/advisories/GHSA-66g8-4hjf-77xh
+
+  Note: these changes remove redundant bold tag nesting which may result
+  in existing rendering tests failing, e.g. rendering "____bold____" to html
+  will no longer yield "<p><strong><strong>bold</strong></strong></p>".
+
+[0.29.0.gfm.9]
+
+  * Cleanup: Use of a private header was cleaned up (#248)
+  * Cleanup: Man page was updated (#255)
+  * Cleanup: Warnings for -Wstrict-prototypes were cleaned up (#285)
+  * Cleanup: We avoid header duplication (#289)
+
+  * We now store positioning info for url_match (#201)
+  * We now expose cmark_parent_footnote_def for non-C renderers (#254)
+  * Footnote aria-label text now reference the specific footnote backref, and we include a data-footnote-backref-idx attribute so the label can be internationalized in a downstream filter (#307)
+
 [0.29.0.gfm.8]
 
   * We restored backwards compatibility by deprecating the `cmark_init_standard_node_flags()` requirement, which is now a noop (#305)
diff --git a/extensions/CMakeLists.txt b/extensions/CMakeLists.txt
index d5b819802..576ad0ba5 100644
--- a/extensions/CMakeLists.txt
+++ b/extensions/CMakeLists.txt
@@ -17,8 +17,6 @@ include_directories(
   ${PROJECT_BINARY_DIR}/src
 )
 
-include (GenerateExportHeader)
-
 include_directories(include ${CMAKE_CURRENT_BINARY_DIR})
 
 set(CMAKE_C_FLAGS_PROFILE "${CMAKE_C_FLAGS_RELEASE} -pg")
@@ -29,6 +27,7 @@ if (CMARK_SHARED)
 
   set_target_properties(${LIBRARY} PROPERTIES
     OUTPUT_NAME "cmark-gfm-extensions"
+    DEFINE_SYMBOL "cmark-gfm"
     SOVERSION ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}.gfm.${PROJECT_VERSION_GFM}
     VERSION ${PROJECT_VERSION})
 
@@ -38,9 +37,6 @@ if (CMARK_SHARED)
   # Avoid name clash between PROGRAM and LIBRARY pdb files.
   set_target_properties(${LIBRARY} PROPERTIES PDB_NAME cmark-gfm-extensions_dll)
 
-  generate_export_header(${LIBRARY}
-    BASE_NAME cmark-gfm-extensions)
-
   list(APPEND CMARK_INSTALL ${LIBRARY})
   target_link_libraries(${LIBRARY} libcmark-gfm)
 
@@ -51,6 +47,7 @@ if (CMARK_STATIC)
 
   set_target_properties(${STATICLIBRARY} PROPERTIES
     COMPILE_FLAGS "-DCMARK_GFM_STATIC_DEFINE -DCMARK_GFM_EXTENSIONS_STATIC_DEFINE"
+    DEFINE_SYMBOL "cmark-gfm"
     POSITION_INDEPENDENT_CODE ON)
 
   if (MSVC)
@@ -63,11 +60,6 @@ if (CMARK_STATIC)
       VERSION ${PROJECT_VERSION})
   endif(MSVC)
 
-  if (NOT CMARK_SHARED)
-    generate_export_header(${STATICLIBRARY}
-      BASE_NAME cmark-gfm-extensions)
-  endif()
-
   list(APPEND CMARK_INSTALL ${STATICLIBRARY})
 endif()
 
@@ -84,7 +76,6 @@ install(TARGETS ${CMARK_INSTALL}
 if (CMARK_SHARED OR CMARK_STATIC)
   install(FILES
   ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm-core-extensions.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/extensions-export.h
   DESTINATION include
   )
 
diff --git a/extensions/autolink.c b/extensions/autolink.c
index f3b75a7e9..491d96c32 100644
--- a/extensions/autolink.c
+++ b/extensions/autolink.c
@@ -267,6 +267,11 @@ static cmark_node *url_match(cmark_parser *parser, cmark_node *parent,
   cmark_node *text = cmark_node_new_with_mem(CMARK_NODE_TEXT, parser->mem);
   text->as.literal = url;
   cmark_node_append_child(node, text);
+  
+  node->start_line = text->start_line = node->end_line = text->end_line = cmark_inline_parser_get_line(inline_parser);
+
+  node->start_column = text->start_column = max_rewind - rewind;
+  node->end_column = text->end_column = cmark_inline_parser_get_column(inline_parser) - 1;
 
   return node;
 }
diff --git a/extensions/include/cmark-gfm-core-extensions.h b/extensions/include/cmark-gfm-core-extensions.h
index d85a89237..6f7aada65 100644
--- a/extensions/include/cmark-gfm-core-extensions.h
+++ b/extensions/include/cmark-gfm-core-extensions.h
@@ -6,40 +6,40 @@ extern "C" {
 #endif
 
 #include "cmark-gfm-extension_api.h"
-#include "extensions-export.h"
-#include "cmark-gfm_config.h" // for bool
+#include "export.h"
+#include <stdbool.h>
 #include <stdint.h>
 
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 void cmark_gfm_core_extensions_ensure_registered(void);
 
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 uint16_t cmark_gfm_extensions_get_table_columns(cmark_node *node);
 
 /** Sets the number of columns for the table, returning 1 on success and 0 on error.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_set_table_columns(cmark_node *node, uint16_t n_columns);
 
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 uint8_t *cmark_gfm_extensions_get_table_alignments(cmark_node *node);
 
 /** Sets the alignments for the table, returning 1 on success and 0 on error.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_set_table_alignments(cmark_node *node, uint16_t ncols, uint8_t *alignments);
 
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_get_table_row_is_header(cmark_node *node);
 
 /** Sets the column span for the table cell, returning 1 on success and 0 on error.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_set_table_cell_colspan(cmark_node *node, unsigned colspan);
 
 /** Sets the row span for the table cell, returning 1 on success and 0 on error.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_set_table_cell_rowspan(cmark_node *node, unsigned rowspan);
 
 /**
@@ -50,7 +50,7 @@ int cmark_gfm_extensions_set_table_cell_rowspan(cmark_node *node, unsigned rowsp
 
  Column span is only parsed when \c CMARK_OPT_TABLE_SPANS is set.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 unsigned cmark_gfm_extensions_get_table_cell_colspan(cmark_node *node);
 
 /**
@@ -61,22 +61,22 @@ unsigned cmark_gfm_extensions_get_table_cell_colspan(cmark_node *node);
 
  Row span is only parsed when \c CMARK_OPT_TABLE_SPANS is set.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 unsigned cmark_gfm_extensions_get_table_cell_rowspan(cmark_node *node);
 
 /** Sets whether the node is a table header row, returning 1 on success and 0 on error.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_set_table_row_is_header(cmark_node *node, int is_header);
 
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 bool cmark_gfm_extensions_get_tasklist_item_checked(cmark_node *node);
 /* For backwards compatibility */
 #define cmark_gfm_extensions_tasklist_is_checked cmark_gfm_extensions_get_tasklist_item_checked
 
 /** Sets whether a tasklist item is "checked" (completed), returning 1 on success and 0 on error.
  */
-CMARK_GFM_EXTENSIONS_EXPORT
+CMARK_GFM_EXPORT
 int cmark_gfm_extensions_set_tasklist_item_checked(cmark_node *node, bool is_checked);
 
 #ifdef __cplusplus
diff --git a/extensions/include/extensions-export.h b/extensions/include/extensions-export.h
deleted file mode 100644
index f91b8564c..000000000
--- a/extensions/include/extensions-export.h
+++ /dev/null
@@ -1,60 +0,0 @@
-#ifndef CMARK_GFM_EXTENSIONS_EXPORT_H
-#define CMARK_GFM_EXTENSIONS_EXPORT_H
-
-#ifdef CMARK_USE_CMAKE_HEADERS
-// if the CMake config header exists, use that instead of this Swift package prebuilt one
-// we need to undefine the header guard, since export.h uses the same one
-#undef CMARK_GFM_EXTENSIONS_EXPORT_H
-#include "cmark-gfm-extensions_export.h"
-#else
-
-#ifdef CMARK_GFM_EXTENSIONS_STATIC_DEFINE
-#  define CMARK_GFM_EXTENSIONS_EXPORT
-#  define CMARK_GFM_EXTENSIONS_NO_EXPORT
-#else
-#  if defined(_WIN32)
-#    ifndef CMARK_GFM_EXTENSIONS_EXPORT
-#      ifdef libcmark_gfm_extensions_EXPORTS
-#        define CMARK_GFM_EXTENSIONS_EXPORT __declspec(dllexport)
-#      else
-#        define CMARK_GFM_EXTENSIONS_EXPORT __declspec(dllimport)
-#      endif
-#    endif
-
-#    ifndef CMARK_GFM_EXTENSIONS_NO_EXPORT
-#      define CMARK_GFM_EXTENSIONS_NO_EXPORT
-#    endif
-#  else
-#    ifndef CMARK_GFM_EXTENSIONS_EXPORT
-#      ifdef libcmark_gfm_extensions_EXPORTS
-#        define CMARK_GFM_EXTENSIONS_EXPORT __attribute__((__visibility__("default")))
-#      else
-#        define CMARK_GFM_EXTENSIONS_EXPORT __attribute__((__visibility__("default")))
-#      endif
-#    endif
-
-#    ifndef CMARK_GFM_EXTENSIONS_NO_EXPORT
-#      define CMARK_GFM_EXTENSIONS_NO_EXPORT __attribute__((__visibility__("hidden")))
-#    endif
-#  endif
-#endif
-
-#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED
-#  if defined(_WIN32)
-#    define CMARK_GFM_EXTENSIONS_DEPRECATED __declspec(deprecated)
-#  else
-#    define CMARK_GFM_EXTENSIONS_DEPRECATED __attribute__ ((__deprecated__))
-#  endif
-#endif
-
-#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED_EXPORT
-#  define CMARK_GFM_EXTENSIONS_DEPRECATED_EXPORT CMARK_GFM_EXTENSIONS_EXPORT CMARK_GFM_EXTENSIONS_DEPRECATED
-#endif
-
-#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED_NO_EXPORT
-#  define CMARK_GFM_EXTENSIONS_DEPRECATED_NO_EXPORT CMARK_GFM_EXTENSIONS_NO_EXPORT CMARK_GFM_EXTENSIONS_DEPRECATED
-#endif
-
-#endif /* CMARK_GFM_EXTENSIONS_EXPORT_H */
-
-#endif /* "cmark-gfm-extensions_export.h" */
diff --git a/fuzz/CMakeLists.txt b/fuzz/CMakeLists.txt
index 3cae79421..a9ed57aa5 100644
--- a/fuzz/CMakeLists.txt
+++ b/fuzz/CMakeLists.txt
@@ -19,3 +19,4 @@ macro(fuzzer name)
 endmacro()
 
 fuzzer(fuzz_quadratic)
+fuzzer(fuzz_quadratic_brackets)
diff --git a/fuzz/fuzz_quadratic.c b/fuzz/fuzz_quadratic.c
index cab1b6330..523c0f444 100644
--- a/fuzz/fuzz_quadratic.c
+++ b/fuzz/fuzz_quadratic.c
@@ -75,8 +75,13 @@ int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
       cmark_parser_feed(parser, markdown, markdown_size);
       cmark_node *doc = cmark_parser_finish(parser);
- 
+
       free(cmark_render_html(doc, fuzz_config.options, NULL));
+      free(cmark_render_xml(doc, fuzz_config.options));
+      free(cmark_render_man(doc, fuzz_config.options, 80));
+      free(cmark_render_commonmark(doc, fuzz_config.options, 80));
+      free(cmark_render_plaintext(doc, fuzz_config.options, 80));
+      free(cmark_render_latex(doc, fuzz_config.options, 80));
 
       cmark_node_free(doc);
       cmark_parser_free(parser);
diff --git a/fuzz/fuzz_quadratic_brackets.c b/fuzz/fuzz_quadratic_brackets.c
new file mode 100644
index 000000000..5c1646464
--- /dev/null
+++ b/fuzz/fuzz_quadratic_brackets.c
@@ -0,0 +1,110 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include "cmark-gfm.h"
+#include "cmark-gfm-core-extensions.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+const char *extension_names[] = {
+  "autolink",
+  "strikethrough",
+  "table",
+  "tagfilter",
+  NULL,
+};
+
+int LLVMFuzzerInitialize(int *argc, char ***argv) {
+  cmark_gfm_core_extensions_ensure_registered();
+  return 0;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  struct __attribute__((packed)) {
+    int options;
+    int width;
+    uint8_t startlen;
+    uint8_t openlen;
+    uint8_t middlelen;
+    uint8_t closelen;
+  } fuzz_config;
+
+  if (size >= sizeof(fuzz_config)) {
+    /* The beginning of `data` is treated as fuzzer configuration */
+    memcpy(&fuzz_config, data, sizeof(fuzz_config));
+
+    /* Test options that are used by GitHub. */
+    fuzz_config.options = CMARK_OPT_UNSAFE | CMARK_OPT_FOOTNOTES | CMARK_OPT_GITHUB_PRE_LANG | CMARK_OPT_HARDBREAKS;
+    fuzz_config.openlen = fuzz_config.openlen & 0x7;
+    fuzz_config.middlelen = fuzz_config.middlelen & 0x7;
+    fuzz_config.closelen = fuzz_config.closelen & 0x7;
+
+    /* Remainder of input is the markdown */
+    const char *markdown0 = (const char *)(data + sizeof(fuzz_config));
+    const size_t markdown_size0 = size - sizeof(fuzz_config);
+    char markdown[0x80000];
+    if (markdown_size0 <= sizeof(markdown)) {
+      size_t markdown_size = 0;
+      const size_t componentslen = fuzz_config.startlen + fuzz_config.openlen + fuzz_config.middlelen + fuzz_config.closelen;
+      if (componentslen <= markdown_size0) {
+        size_t offset = 0;
+        const size_t endlen = markdown_size0 - componentslen;
+        memcpy(&markdown[markdown_size], &markdown0[offset], fuzz_config.startlen);
+        markdown_size += fuzz_config.startlen;
+        offset += fuzz_config.startlen;
+
+        if (0 < fuzz_config.openlen) {
+          while (markdown_size + fuzz_config.openlen <= sizeof(markdown)/2) {
+            memcpy(&markdown[markdown_size], &markdown0[offset],
+                   fuzz_config.openlen);
+            markdown_size += fuzz_config.openlen;
+          }
+          offset += fuzz_config.openlen;
+        }
+        memcpy(&markdown[markdown_size], &markdown0[offset],
+               fuzz_config.middlelen);
+        markdown_size += fuzz_config.middlelen;
+        offset += fuzz_config.middlelen;
+        if (0 < fuzz_config.closelen) {
+          while (markdown_size + fuzz_config.closelen + endlen <= sizeof(markdown)) {
+            memcpy(&markdown[markdown_size], &markdown0[offset],
+                   fuzz_config.closelen);
+            markdown_size += fuzz_config.closelen;
+          }
+          offset += fuzz_config.closelen;
+        }
+        if (markdown_size + endlen <= sizeof(markdown)) {
+          memcpy(&markdown[markdown_size], &markdown0[offset],
+                 endlen);
+          markdown_size += endlen;
+        }
+      } else {
+        markdown_size = markdown_size0;
+        memcpy(markdown, markdown0, markdown_size);
+      }
+
+      cmark_parser *parser = cmark_parser_new(fuzz_config.options);
+
+      for (const char **it = extension_names; *it; ++it) {
+        const char *extension_name = *it;
+        cmark_syntax_extension *syntax_extension = cmark_find_syntax_extension(extension_name);
+        if (!syntax_extension) {
+          fprintf(stderr, "%s is not a valid syntax extension\n", extension_name);
+          abort();
+        }
+        cmark_parser_attach_syntax_extension(parser, syntax_extension);
+      }
+
+      cmark_parser_feed(parser, markdown, markdown_size);
+      cmark_node *doc = cmark_parser_finish(parser);
+ 
+      free(cmark_render_html(doc, fuzz_config.options, NULL));
+
+      cmark_node_free(doc);
+      cmark_parser_free(parser);
+    }
+  }
+  return 0;
+}
diff --git a/man/man1/cmark-gfm.1 b/man/man1/cmark-gfm.1
index 5c68d79c3..4fca62732 100644
--- a/man/man1/cmark-gfm.1
+++ b/man/man1/cmark-gfm.1
@@ -58,10 +58,10 @@ be rendered as curly quotes, depending on their position.
 \f[C]\-\-\-\f[] will be rendered as an em-dash.
 \f[C]...\f[] will be rendered as ellipses.
 .TP 12n
-.B \-\-safe
-Do not render raw HTML or potentially dangerous URLs.
-(Raw HTML is replaced by a placeholder comment; potentially
-dangerous URLs are replaced by empty strings.)  Dangerous
+.B \-\-unsafe
+Render raw HTML and potentially dangerous URLs.
+(Raw HTML is not replaced by a placeholder comment; potentially
+dangerous URLs are not replaced by empty strings.)  Dangerous
 URLs are those that begin with `javascript:`, `vbscript:`,
 `file:`, or `data:` (except for `image/png`, `image/gif`,
 `image/jpeg`, or `image/webp` mime types).
diff --git a/src/arena.c b/src/arena.c
index c1cea10eb..86bf5b749 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -118,6 +118,6 @@ static void arena_free(void *ptr) {
 
 cmark_mem CMARK_ARENA_MEM_ALLOCATOR = {arena_calloc, arena_realloc, arena_free};
 
-cmark_mem *cmark_get_arena_mem_allocator() {
+cmark_mem *cmark_get_arena_mem_allocator(void) {
   return &CMARK_ARENA_MEM_ALLOCATOR;
 }
diff --git a/src/blocks.c b/src/blocks.c
index 49bcbce39..a7290652c 100644
--- a/src/blocks.c
+++ b/src/blocks.c
@@ -27,6 +27,14 @@
 #define CODE_INDENT 4
 #define TAB_STOP 4
 
+/**
+ * Very deeply nested lists can cause quadratic performance issues.
+ * This constant is used in open_new_blocks() to limit the nesting
+ * depth. It is unlikely that a non-contrived markdown document will
+ * be nested this deeply.
+ */
+#define MAX_LIST_DEPTH 100
+
 #ifndef MIN
 #define MIN(x, y) ((x < y) ? x : y)
 #endif
@@ -1148,10 +1156,11 @@ static void open_new_blocks(cmark_parser *parser, cmark_node **container,
   bool has_content;
   int save_offset;
   int save_column;
+  size_t depth = 0;
 
   while (cont_type != CMARK_NODE_CODE_BLOCK &&
          cont_type != CMARK_NODE_HTML_BLOCK) {
-
+    depth++;
     S_find_first_nonspace(parser, input);
     indented = parser->indent >= CODE_INDENT;
 
@@ -1253,6 +1262,7 @@ static void open_new_blocks(cmark_parser *parser, cmark_node **container,
       (*container)->internal_offset = matched;
     } else if ((!indented || cont_type == CMARK_NODE_LIST) &&
 	       parser->indent < 4 &&
+               depth < MAX_LIST_DEPTH &&
                (matched = parse_list_marker(
                     parser->mem, input, parser->first_nonspace,
                     (*container)->type == CMARK_NODE_PARAGRAPH, &data))) {
diff --git a/src/cmark.c b/src/cmark.c
index 08477fa57..f2619f429 100644
--- a/src/cmark.c
+++ b/src/cmark.c
@@ -10,9 +10,9 @@
 cmark_node_type CMARK_NODE_LAST_BLOCK = CMARK_NODE_FOOTNOTE_DEFINITION;
 cmark_node_type CMARK_NODE_LAST_INLINE = CMARK_NODE_ATTRIBUTE;
 
-int cmark_version() { return CMARK_GFM_VERSION; }
+int cmark_version(void) { return CMARK_GFM_VERSION; }
 
-const char *cmark_version_string() { return CMARK_GFM_VERSION_STRING; }
+const char *cmark_version_string(void) { return CMARK_GFM_VERSION_STRING; }
 
 static void *xcalloc(size_t nmem, size_t size) {
   void *ptr = calloc(nmem, size);
@@ -38,7 +38,7 @@ static void xfree(void *ptr) {
 
 cmark_mem CMARK_DEFAULT_MEM_ALLOCATOR = {xcalloc, xrealloc, xfree};
 
-cmark_mem *cmark_get_default_mem_allocator() {
+cmark_mem *cmark_get_default_mem_allocator(void) {
   return &CMARK_DEFAULT_MEM_ALLOCATOR;
 }
 
diff --git a/src/commonmark.c b/src/commonmark.c
index 328da12a3..d296567e0 100644
--- a/src/commonmark.c
+++ b/src/commonmark.c
@@ -154,23 +154,8 @@ static bool is_autolink(cmark_node *node) {
                   link_text->as.literal.len) == 0);
 }
 
-// if node is a block node, returns node.
-// otherwise returns first block-level node that is an ancestor of node.
-// if there is no block-level ancestor, returns NULL.
-static cmark_node *get_containing_block(cmark_node *node) {
-  while (node) {
-    if (CMARK_NODE_BLOCK_P(node)) {
-      return node;
-    } else {
-      node = node->parent;
-    }
-  }
-  return NULL;
-}
-
 static int S_render_node(cmark_renderer *renderer, cmark_node *node,
                          cmark_event_type ev_type, int options) {
-  cmark_node *tmp;
   int list_number;
   cmark_delim_type list_delim;
   int numticks;
@@ -190,14 +175,17 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
   // Don't adjust tight list status til we've started the list.
   // Otherwise we loose the blank line between a paragraph and
   // a following list.
-  if (!(node->type == CMARK_NODE_ITEM && node->prev == NULL && entering)) {
-    tmp = get_containing_block(node);
-    renderer->in_tight_list_item =
-        tmp && // tmp might be NULL if there is no containing block
-        ((tmp->type == CMARK_NODE_ITEM &&
-          cmark_node_get_list_tight(tmp->parent)) ||
-         (tmp && tmp->parent && tmp->parent->type == CMARK_NODE_ITEM &&
-          cmark_node_get_list_tight(tmp->parent->parent)));
+  if (entering) {
+    if (node->parent && node->parent->type == CMARK_NODE_ITEM) {
+      renderer->in_tight_list_item = node->parent->parent->as.list.tight;
+    }
+  } else {
+    if (node->type == CMARK_NODE_LIST) {
+      renderer->in_tight_list_item =
+        node->parent &&
+        node->parent->type == CMARK_NODE_ITEM &&
+        node->parent->parent->as.list.tight;
+    }
   }
 
   if (node->extension && node->extension->commonmark_render_func) {
@@ -235,13 +223,8 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {
       marker_width = 4;
     } else {
-      list_number = cmark_node_get_list_start(node->parent);
+      list_number = cmark_node_get_item_index(node);
       list_delim = cmark_node_get_list_delim(node->parent);
-      tmp = node;
-      while (tmp->prev) {
-        tmp = tmp->prev;
-        list_number += 1;
-      }
       // we ensure a width of at least 4 so
       // we get nice transition from single digits
       // to double
@@ -406,10 +389,12 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     break;
 
   case CMARK_NODE_STRONG:
-    if (entering) {
-      LIT("**");
-    } else {
-      LIT("**");
+    if (node->parent == NULL || node->parent->type != CMARK_NODE_STRONG) {
+      if (entering) {
+        LIT("**");
+      } else {
+        LIT("**");
+      }
     }
     break;
 
diff --git a/src/html.c b/src/html.c
index 96daa18e2..f1f2ff774 100644
--- a/src/html.c
+++ b/src/html.c
@@ -63,10 +63,16 @@ static bool S_put_footnote_backref(cmark_html_renderer *renderer, cmark_strbuf *
   if (renderer->written_footnote_ix >= renderer->footnote_ix)
     return false;
   renderer->written_footnote_ix = renderer->footnote_ix;
+  char m[32];
+  snprintf(m, sizeof(m), "%d", renderer->written_footnote_ix);
 
   cmark_strbuf_puts(html, "<a href=\"#fnref-");
   houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
-  cmark_strbuf_puts(html, "\" class=\"footnote-backref\" data-footnote-backref aria-label=\"Back to content\">↩</a>");
+  cmark_strbuf_puts(html, "\" class=\"footnote-backref\" data-footnote-backref data-footnote-backref-idx=\"");
+  cmark_strbuf_puts(html, m);
+  cmark_strbuf_puts(html, "\" aria-label=\"Back to reference ");
+  cmark_strbuf_puts(html, m);
+  cmark_strbuf_puts(html, "\">↩</a>");
 
   if (node->footnote.def_count > 1)
   {
@@ -78,7 +84,15 @@ static bool S_put_footnote_backref(cmark_html_renderer *renderer, cmark_strbuf *
       houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
       cmark_strbuf_puts(html, "-");
       cmark_strbuf_puts(html, n);
-      cmark_strbuf_puts(html, "\" class=\"footnote-backref\" data-footnote-backref aria-label=\"Back to content\">↩<sup class=\"footnote-ref\">");
+      cmark_strbuf_puts(html, "\" class=\"footnote-backref\" data-footnote-backref data-footnote-backref-idx=\"");
+      cmark_strbuf_puts(html, m);
+      cmark_strbuf_puts(html, "-");
+      cmark_strbuf_puts(html, n);
+      cmark_strbuf_puts(html, "\" aria-label=\"Back to reference ");
+      cmark_strbuf_puts(html, m);
+      cmark_strbuf_puts(html, "-");
+      cmark_strbuf_puts(html, n);
+      cmark_strbuf_puts(html, "\">↩<sup class=\"footnote-ref\">");
       cmark_strbuf_puts(html, n);
       cmark_strbuf_puts(html, "</sup></a>");
     }
@@ -350,10 +364,12 @@ static int S_render_node(cmark_html_renderer *renderer, cmark_node *node,
     break;
 
   case CMARK_NODE_STRONG:
-    if (entering) {
-      cmark_strbuf_puts(html, "<strong>");
-    } else {
-      cmark_strbuf_puts(html, "</strong>");
+    if (node->parent == NULL || node->parent->type != CMARK_NODE_STRONG) {
+      if (entering) {
+        cmark_strbuf_puts(html, "<strong>");
+      } else {
+        cmark_strbuf_puts(html, "</strong>");
+      }
     }
     break;
 
diff --git a/src/include/cmark-gfm.h b/src/include/cmark-gfm.h
index 4513a19a1..43b8893c8 100644
--- a/src/include/cmark-gfm.h
+++ b/src/include/cmark-gfm.h
@@ -230,6 +230,11 @@ CMARK_GFM_EXPORT cmark_node *cmark_node_last_child(cmark_node *node);
  */
 CMARK_GFM_EXPORT cmark_node *cmark_node_nth_child(cmark_node *node, int n);
 
+/** Returns the footnote reference of 'node', or NULL if 'node' doesn't have a
+ * footnote reference.
+ */
+CMARK_GFM_EXPORT cmark_node *cmark_node_parent_footnote_def(cmark_node *node);
+
 /**
  * ## Iterator
  *
@@ -418,6 +423,17 @@ CMARK_GFM_EXPORT int cmark_node_get_list_tight(cmark_node *node);
  */
 CMARK_GFM_EXPORT int cmark_node_set_list_tight(cmark_node *node, int tight);
 
+/**
+ * Returns item index of 'node'. This is only used when rendering output
+ * formats such as commonmark, which need to output the index. It is not
+ * required for formats such as html or latex.
+ */
+CMARK_GFM_EXPORT int cmark_node_get_item_index(cmark_node *node);
+
+/** Sets item index of 'node'. Returns 1 on success, 0 on failure.
+ */
+CMARK_GFM_EXPORT int cmark_node_set_item_index(cmark_node *node, int idx);
+
 /** Returns the info string from a fenced code block.
  */
 CMARK_GFM_EXPORT const char *cmark_node_get_fence_info(cmark_node *node);
diff --git a/src/include/node.h b/src/include/node.h
index e4a849965..76c5b7992 100644
--- a/src/include/node.h
+++ b/src/include/node.h
@@ -87,6 +87,14 @@ struct cmark_node {
 
   cmark_syntax_extension *extension;
 
+  /**
+   * Used during cmark_render() to cache the most recent non-NULL
+   * extension, if you go up the parent chain like this:
+   *
+   * node->parent->...parent->extension
+   */
+  cmark_syntax_extension *ancestor_extension;
+
   union {
     int ref_ix;
     int def_count;
@@ -125,7 +133,7 @@ void cmark_register_node_flag(cmark_node_internal_flags *flags);
  * library. It is now a no-op.
  */
 CMARK_GFM_EXPORT
-void cmark_init_standard_node_flags();
+void cmark_init_standard_node_flags(void);
 
 static CMARK_INLINE cmark_mem *cmark_node_mem(cmark_node *node) {
   return node->content.mem;
@@ -150,6 +158,13 @@ static CMARK_INLINE bool CMARK_NODE_INLINE_P(cmark_node *node) {
 
 CMARK_GFM_EXPORT bool cmark_node_can_contain_type(cmark_node *node, cmark_node_type child_type);
 
+/**
+ * Enable (or disable) extra safety checks. These extra checks cause
+ * extra performance overhead (in some cases quadratic), so they are only
+ * intended to be used during testing.
+ */
+CMARK_GFM_EXPORT void cmark_enable_safety_checks(bool enable);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/latex.c b/src/latex.c
index c204f6003..87e7dd32b 100644
--- a/src/latex.c
+++ b/src/latex.c
@@ -385,10 +385,12 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     break;
 
   case CMARK_NODE_STRONG:
-    if (entering) {
-      LIT("\\textbf{");
-    } else {
-      LIT("}");
+    if (node->parent == NULL || node->parent->type != CMARK_NODE_STRONG) {
+      if (entering) {
+        LIT("\\textbf{");
+      } else {
+        LIT("}");
+      }
     }
     break;
 
diff --git a/src/man.c b/src/man.c
index c60e1bfe7..b92cbd803 100644
--- a/src/man.c
+++ b/src/man.c
@@ -74,7 +74,6 @@ static void S_outc(cmark_renderer *renderer, cmark_node *node,
 
 static int S_render_node(cmark_renderer *renderer, cmark_node *node,
                          cmark_event_type ev_type, int options) {
-  cmark_node *tmp;
   int list_number;
   bool entering = (ev_type == CMARK_EVENT_ENTER);
   bool allow_wrap = renderer->width > 0 && !(CMARK_OPT_NOBREAKS & options);
@@ -123,12 +122,7 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
       if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {
         LIT("\\[bu] 2");
       } else {
-        list_number = cmark_node_get_list_start(node->parent);
-        tmp = node;
-        while (tmp->prev) {
-          tmp = tmp->prev;
-          list_number += 1;
-        }
+        list_number = cmark_node_get_item_index(node);
         char list_number_s[LIST_NUMBER_SIZE];
         snprintf(list_number_s, LIST_NUMBER_SIZE, "\"%d.\" 4", list_number);
         LIT(list_number_s);
@@ -225,10 +219,12 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     break;
 
   case CMARK_NODE_STRONG:
-    if (entering) {
-      LIT("\\f[B]");
-    } else {
-      LIT("\\f[]");
+    if (node->parent == NULL || node->parent->type != CMARK_NODE_STRONG) {
+      if (entering) {
+        LIT("\\f[B]");
+      } else {
+        LIT("\\f[]");
+      }
     }
     break;
 
diff --git a/src/node.c b/src/node.c
index a4b67121e..d93ed307d 100644
--- a/src/node.c
+++ b/src/node.c
@@ -7,6 +7,30 @@
 #include "syntax_extension.h"
 
 CMARK_DEFINE_LOCK(nextflag)
+CMARK_DEFINE_LOCK(safety)
+
+/**
+ * Expensive safety checks are off by default, but can be enabled
+ * by calling cmark_enable_safety_checks().
+ */
+static bool enable_safety_checks = false;
+
+void cmark_enable_safety_checks(bool enable) {
+  CMARK_INITIALIZE_AND_LOCK(safety);
+  enable_safety_checks = enable;
+  CMARK_UNLOCK(safety);
+}
+
+/**
+ * Check whether safety checks have been enabled in a function to guard access
+ * behind a lock.
+ */
+static bool S_safety_checks_enabled() {
+  CMARK_INITIALIZE_AND_LOCK(safety);
+  bool safety_enabled = enable_safety_checks;
+  CMARK_UNLOCK(safety);
+  return safety_enabled;
+}
 
 static void S_node_unlink(cmark_node *node);
 
@@ -36,7 +60,7 @@ void cmark_register_node_flag(cmark_node_internal_flags *flags) {
   CMARK_UNLOCK(nextflag);
 }
 
-void cmark_init_standard_node_flags() {}
+void cmark_init_standard_node_flags(void) {}
 
 bool cmark_node_can_contain_type(cmark_node *node, cmark_node_type child_type) {
   if (child_type == CMARK_NODE_DOCUMENT) {
@@ -78,8 +102,6 @@ bool cmark_node_can_contain_type(cmark_node *node, cmark_node_type child_type) {
 }
 
 static bool S_can_contain(cmark_node *node, cmark_node *child) {
-  cmark_node *cur;
-
   if (node == NULL || child == NULL) {
     return false;
   }
@@ -87,14 +109,16 @@ static bool S_can_contain(cmark_node *node, cmark_node *child) {
     return 0;
   }
 
-  // Verify that child is not an ancestor of node or equal to node.
-  cur = node;
-  do {
-    if (cur == child) {
-      return false;
-    }
-    cur = cur->parent;
-  } while (cur != NULL);
+  if (S_safety_checks_enabled()) {
+    // Verify that child is not an ancestor of node or equal to node.
+    cmark_node *cur = node;
+    do {
+      if (cur == child) {
+        return false;
+      }
+      cur = cur->parent;
+    } while (cur != NULL);
+  }
 
   return cmark_node_can_contain_type(node, (cmark_node_type) child->type);
 }
@@ -349,6 +373,14 @@ cmark_node *cmark_node_nth_child(cmark_node *node, int n) {
   return ret;
 }
 
+cmark_node *cmark_node_parent_footnote_def(cmark_node *node) {
+  if (node == NULL) {
+    return NULL;
+  } else {
+    return node->parent_footnote_def;
+  }
+}
+
 void *cmark_node_get_user_data(cmark_node *node) {
   if (node == NULL) {
     return NULL;
@@ -576,6 +608,31 @@ int cmark_node_set_list_tight(cmark_node *node, int tight) {
   }
 }
 
+int cmark_node_get_item_index(cmark_node *node) {
+  if (node == NULL) {
+    return 0;
+  }
+
+  if (node->type == CMARK_NODE_ITEM) {
+    return node->as.list.start;
+  } else {
+    return 0;
+  }
+}
+
+int cmark_node_set_item_index(cmark_node *node, int idx) {
+  if (node == NULL || idx < 0) {
+    return 0;
+  }
+
+  if (node->type == CMARK_NODE_ITEM) {
+    node->as.list.start = idx;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
 const char *cmark_node_get_fence_info(cmark_node *node) {
   if (node == NULL) {
     return NULL;
diff --git a/src/plaintext.c b/src/plaintext.c
index 0edbd1406..c9aa0fd6e 100644
--- a/src/plaintext.c
+++ b/src/plaintext.c
@@ -16,23 +16,8 @@ static CMARK_INLINE void outc(cmark_renderer *renderer, cmark_node *node,
   cmark_render_code_point(renderer, c);
 }
 
-// if node is a block node, returns node.
-// otherwise returns first block-level node that is an ancestor of node.
-// if there is no block-level ancestor, returns NULL.
-static cmark_node *get_containing_block(cmark_node *node) {
-  while (node) {
-    if (CMARK_NODE_BLOCK_P(node)) {
-      return node;
-    } else {
-      node = node->parent;
-    }
-  }
-  return NULL;
-}
-
 static int S_render_node(cmark_renderer *renderer, cmark_node *node,
                          cmark_event_type ev_type, int options) {
-  cmark_node *tmp;
   int list_number;
   cmark_delim_type list_delim;
   int i;
@@ -46,14 +31,17 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
   // Don't adjust tight list status til we've started the list.
   // Otherwise we loose the blank line between a paragraph and
   // a following list.
-  if (!(node->type == CMARK_NODE_ITEM && node->prev == NULL && entering)) {
-    tmp = get_containing_block(node);
-    renderer->in_tight_list_item =
-        tmp && // tmp might be NULL if there is no containing block
-        ((tmp->type == CMARK_NODE_ITEM &&
-          cmark_node_get_list_tight(tmp->parent)) ||
-         (tmp && tmp->parent && tmp->parent->type == CMARK_NODE_ITEM &&
-          cmark_node_get_list_tight(tmp->parent->parent)));
+  if (entering) {
+    if (node->parent && node->parent->type == CMARK_NODE_ITEM) {
+      renderer->in_tight_list_item = node->parent->parent->as.list.tight;
+    }
+  } else {
+    if (node->type == CMARK_NODE_LIST) {
+      renderer->in_tight_list_item =
+        node->parent &&
+        node->parent->type == CMARK_NODE_ITEM &&
+        node->parent->parent->as.list.tight;
+    }
   }
 
   if (node->extension && node->extension->plaintext_render_func) {
@@ -79,13 +67,8 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {
       marker_width = 4;
     } else {
-      list_number = cmark_node_get_list_start(node->parent);
+      list_number = cmark_node_get_item_index(node);
       list_delim = cmark_node_get_list_delim(node->parent);
-      tmp = node;
-      while (tmp->prev) {
-        tmp = tmp->prev;
-        list_number += 1;
-      }
       // we ensure a width of at least 4 so
       // we get nice transition from single digits
       // to double
diff --git a/src/render.c b/src/render.c
index 02e9e838b..1a0d2ae8d 100644
--- a/src/render.c
+++ b/src/render.c
@@ -31,13 +31,7 @@ static void S_out(cmark_renderer *renderer, cmark_node *node,
   cmark_chunk remainder = cmark_chunk_literal("");
   int k = renderer->buffer->size - 1;
 
-  cmark_syntax_extension *ext = NULL;
-  cmark_node *n = node;
-  while (n && !ext) {
-    ext = n->extension;
-    if (!ext)
-      n = n->parent;
-  }
+  cmark_syntax_extension *ext = node->ancestor_extension;
   if (ext && !ext->commonmark_escape_func)
     ext = NULL;
 
@@ -182,6 +176,20 @@ char *cmark_render(cmark_mem *mem, cmark_node *root, int options, int width,
 
   while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
     cur = cmark_iter_get_node(iter);
+    if (cur->extension) {
+      cur->ancestor_extension = cur->extension;
+    } else if (cur->parent) {
+      cur->ancestor_extension = cur->parent->ancestor_extension;
+    }
+    if (cur->type == CMARK_NODE_ITEM) {
+      // Calculate the list item's index, for the benefit of output formats
+      // like commonmark and plaintext.
+      if (cur->prev) {
+        cmark_node_set_item_index(cur, 1 + cmark_node_get_item_index(cur->prev));
+      } else {
+        cmark_node_set_item_index(cur, cmark_node_get_list_start(cur->parent));
+      }
+    }
     if (!render_node(&renderer, cur, ev_type, options)) {
       // a false value causes us to skip processing
       // the node's contents.  this is used for
diff --git a/src/xml.c b/src/xml.c
index d572290ae..184bff486 100644
--- a/src/xml.c
+++ b/src/xml.c
@@ -11,6 +11,7 @@
 #include "syntax_extension.h"
 
 #define BUFFER_SIZE 100
+#define MAX_INDENT 40
 
 // Functions to convert cmark_nodes to XML strings.
 
@@ -26,7 +27,7 @@ struct render_state {
 
 static CMARK_INLINE void indent(struct render_state *state) {
   int i;
-  for (i = 0; i < state->indent; i++) {
+  for (i = 0; i < state->indent && i < MAX_INDENT; i++) {
     cmark_strbuf_putc(state->xml, ' ');
   }
 }
diff --git a/test/extensions.txt b/test/extensions.txt
index a1a150faa..fe98fe548 100644
--- a/test/extensions.txt
+++ b/test/extensions.txt
@@ -737,7 +737,7 @@ Hi!
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-1">
-<p>Some <em>bolded</em> footnote definition. <a href="#fnref-1" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>Some <em>bolded</em> footnote definition. <a href="#fnref-1" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a></p>
 </li>
 <li id="fn-footnote">
 <blockquote>
@@ -745,15 +745,15 @@ Hi!
 </blockquote>
 <pre><code>as well as code blocks
 </code></pre>
-<p>or, naturally, simple paragraphs. <a href="#fnref-footnote" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>or, naturally, simple paragraphs. <a href="#fnref-footnote" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="2" aria-label="Back to reference 2">↩</a></p>
 </li>
 <li id="fn-other-note">
-<p>no code block here (spaces are stripped away) <a href="#fnref-other-note" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>no code block here (spaces are stripped away) <a href="#fnref-other-note" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="3" aria-label="Back to reference 3">↩</a></p>
 </li>
 <li id="fn-codeblock-note">
 <pre><code>this is now a code block (8 spaces indentation)
 </code></pre>
-<a href="#fnref-codeblock-note" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a>
+<a href="#fnref-codeblock-note" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="4" aria-label="Back to reference 4">↩</a>
 </li>
 </ol>
 </section>
@@ -773,7 +773,7 @@ This footnote is referenced[^a-footnote] multiple times, in lots of different pl
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-a-footnote">
-<p>This footnote definition should have three backrefs. <a href="#fnref-a-footnote" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a> <a href="#fnref-a-footnote-2" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩<sup class="footnote-ref">2</sup></a> <a href="#fnref-a-footnote-3" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩<sup class="footnote-ref">3</sup></a></p>
+<p>This footnote definition should have three backrefs. <a href="#fnref-a-footnote" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a> <a href="#fnref-a-footnote-2" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1-2" aria-label="Back to reference 1-2">↩<sup class="footnote-ref">2</sup></a> <a href="#fnref-a-footnote-3" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1-3" aria-label="Back to reference 1-3">↩<sup class="footnote-ref">3</sup></a></p>
 </li>
 </ol>
 </section>
@@ -790,7 +790,7 @@ Hello[^"><script>alert(1)</script>]
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-%22%3E%3Cscript%3Ealert(1)%3C/script%3E">
-<p>pwned <a href="#fnref-%22%3E%3Cscript%3Ealert(1)%3C/script%3E" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>pwned <a href="#fnref-%22%3E%3Cscript%3Ealert(1)%3C/script%3E" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a></p>
 </li>
 </ol>
 </section>
diff --git a/test/regression.txt b/test/regression.txt
index 844da60a2..0ec493d3d 100644
--- a/test/regression.txt
+++ b/test/regression.txt
@@ -4,8 +4,7 @@ Issue #113: EOL character weirdness on Windows
 (Important: first line ends with CR + CR + LF)
 
 ```````````````````````````````` example
-line1
-
+line1

 line2
 .
 <p>line1</p>
@@ -194,7 +193,7 @@ A footnote in a paragraph[^1]
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-1">
-<p>a footnote <a href="#fnref-1" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a> <a href="#fnref-1-2" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩<sup class="footnote-ref">2</sup></a></p>
+<p>a footnote <a href="#fnref-1" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a> <a href="#fnref-1-2" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1-2" aria-label="Back to reference 1-2">↩<sup class="footnote-ref">2</sup></a></p>
 </li>
 </ol>
 </section>
@@ -284,10 +283,10 @@ This is some text. It has a citation.[^citation]
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-citation">
-<p>This is a long winded parapgraph that also has another citation.<sup class="footnote-ref"><a href="#fn-another-citation" id="fnref-another-citation" data-footnote-ref>2</a></sup> <a href="#fnref-citation" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>This is a long winded parapgraph that also has another citation.<sup class="footnote-ref"><a href="#fn-another-citation" id="fnref-another-citation" data-footnote-ref>2</a></sup> <a href="#fnref-citation" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a></p>
 </li>
 <li id="fn-another-citation">
-<p>My second citation. <a href="#fnref-another-citation" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>My second citation. <a href="#fnref-another-citation" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="2" aria-label="Back to reference 2">↩</a></p>
 </li>
 </ol>
 </section>
@@ -306,10 +305,10 @@ This is some text. It has two footnotes references, side-by-side without any spa
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-footnote1">
-<p>Hello. <a href="#fnref-footnote1" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>Hello. <a href="#fnref-footnote1" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a></p>
 </li>
 <li id="fn-footnote2">
-<p>Goodbye. <a href="#fnref-footnote2" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>Goodbye. <a href="#fnref-footnote2" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="2" aria-label="Back to reference 2">↩</a></p>
 </li>
 </ol>
 </section>
@@ -331,10 +330,10 @@ It has another footnote that contains many different characters (the autolinker
 <section class="footnotes" data-footnotes>
 <ol>
 <li id="fn-widely-cited">
-<p>this renders properly. <a href="#fnref-widely-cited" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>this renders properly. <a href="#fnref-widely-cited" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="1" aria-label="Back to reference 1">↩</a></p>
 </li>
 <li id="fn-sphinx-of-black-quartz_judge-my-vow-0123456789">
-<p>so does this. <a href="#fnref-sphinx-of-black-quartz_judge-my-vow-0123456789" class="footnote-backref" data-footnote-backref aria-label="Back to content">↩</a></p>
+<p>so does this. <a href="#fnref-sphinx-of-black-quartz_judge-my-vow-0123456789" class="footnote-backref" data-footnote-backref data-footnote-backref-idx="2" aria-label="Back to reference 2">↩</a></p>
 </li>
 </ol>
 </section>
diff --git a/test/spec.txt b/test/spec.txt
index eaab9032d..d42f3369e 100644
--- a/test/spec.txt
+++ b/test/spec.txt
@@ -6926,7 +6926,7 @@ foo__bar__
 ```````````````````````````````` example
 __foo, __bar__, baz__
 .
-<p><strong>foo, <strong>bar</strong>, baz</strong></p>
+<p><strong>foo, bar, baz</strong></p>
 ````````````````````````````````
 
 
@@ -7197,7 +7197,7 @@ foo***bar***baz
 ```````````````````````````````` example
 foo******bar*********baz
 .
-<p>foo<strong><strong><strong>bar</strong></strong></strong>***baz</p>
+<p>foo<strong>bar</strong>***baz</p>
 ````````````````````````````````
 
 
@@ -7268,21 +7268,21 @@ __foo _bar_ baz__
 ```````````````````````````````` example
 __foo __bar__ baz__
 .
-<p><strong>foo <strong>bar</strong> baz</strong></p>
+<p><strong>foo bar baz</strong></p>
 ````````````````````````````````
 
 
 ```````````````````````````````` example
 ____foo__ bar__
 .
-<p><strong><strong>foo</strong> bar</strong></p>
+<p><strong>foo bar</strong></p>
 ````````````````````````````````
 
 
 ```````````````````````````````` example
 **foo **bar****
 .
-<p><strong>foo <strong>bar</strong></strong></p>
+<p><strong>foo bar</strong></p>
 ````````````````````````````````
 
 
@@ -7567,14 +7567,14 @@ switching delimiters:
 ```````````````````````````````` example
 ****foo****
 .
-<p><strong><strong>foo</strong></strong></p>
+<p><strong>foo</strong></p>
 ````````````````````````````````
 
 
 ```````````````````````````````` example
 ____foo____
 .
-<p><strong><strong>foo</strong></strong></p>
+<p><strong>foo</strong></p>
 ````````````````````````````````
 
 
@@ -7585,7 +7585,7 @@ delimiters:
 ```````````````````````````````` example
 ******foo******
 .
-<p><strong><strong><strong>foo</strong></strong></strong></p>
+<p><strong>foo</strong></p>
 ````````````````````````````````
 
 
@@ -7601,7 +7601,7 @@ Rule 14:
 ```````````````````````````````` example
 _____foo_____
 .
-<p><em><strong><strong>foo</strong></strong></em></p>
+<p><em><strong>foo</strong></em></p>
 ````````````````````````````````