diff --git a/.gitignore b/.gitignore
index 01cd39276..ad9680b88 100644
--- a/.gitignore
+++ b/.gitignore
@@ -127,6 +127,7 @@ src/misc/*.o
 /test/test_metatile
 /test/test_coord_conversion
 /test/test_babel
+/test/test_time
 
 # /po/
 /po/Makefile.in.in
diff --git a/test/Makefile.am b/test/Makefile.am
index 762a08119..790c02d79 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -20,6 +20,7 @@ endif
 check_PROGRAMS = degrees_converter \
 	gpx2gpx \
 	test_vikgotoxmltool \
+	test_time \
 	test_coord_conversion \
 	test_babel \
 	test_md5_hash \
@@ -78,6 +79,11 @@ test_vikgotoxmltool_LDADD = \
   $(top_builddir)/src/libviking.a \
   $(LDADD)
 
+test_time_SOURCES = test_time.c
+test_time_LDADD = \
+  $(top_builddir)/src/libviking.a \
+  $(LDADD)
+
 test_coord_conversion_SOURCES = test_coord_conversion.c
 test_coord_conversion_LDADD = \
   $(top_builddir)/src/libviking.a \
diff --git a/test/test_time.c b/test/test_time.c
new file mode 100644
index 000000000..34be300a6
--- /dev/null
+++ b/test/test_time.c
@@ -0,0 +1,47 @@
+// Copyright: CC0
+// Compare timegm() with util_timegm()
+//  NB Need to force util_timegm() to use our fallback version
+//  Otherwise it will be using timegm()
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <time.h>
+#include "util.h"
+
+// run like - 'for now':
+//  ./test_time $(date +"%Y:%m:%d-%H:%M:%S")
+// Or manually substitute interesting dates as appropriate
+//  e.g.  '2400:03:01-10:11:12'
+int main(int argc, char *argv[])
+{
+#if !GLIB_CHECK_VERSION(2,36,0)
+  g_type_init ();
+#endif
+
+  if ( !argv[1] ) {
+    g_printerr ( "Nothing specified\n" );
+    return 1;
+  }
+
+  struct tm Time;
+  Time.tm_wday = 0;
+  Time.tm_yday = 0;
+  Time.tm_isdst = 0; // there is no DST in UTC
+
+  sscanf(argv[1], "%d:%d:%d-%d:%d:%d",
+                  &Time.tm_year, &Time.tm_mon,
+                  &Time.tm_mday, &Time.tm_hour,
+                  &Time.tm_min, &Time.tm_sec);
+
+  Time.tm_year -= 1900;
+  Time.tm_mon  -= 1;
+
+  time_t thetime = util_timegm ( &Time );
+
+  if ( thetime != timegm ( &Time ) ) {
+    g_printf ("%s - %lu - %lu\n", argv[1], thetime, timegm(&Time));
+    g_printf ("diff = %ld\n", (thetime - timegm(&Time)));
+    return 1;
+  }
+
+  return 0;
+}