diff --git a/lib/src/callable/async.dart b/lib/src/callable/async.dart
index 30a4cd9bf..00acb0c4a 100644
--- a/lib/src/callable/async.dart
+++ b/lib/src/callable/async.dart
@@ -4,8 +4,6 @@
 
 import 'dart:async';
 
-import 'package:async/async.dart';
-
 import '../value.dart';
 import '../value/external/value.dart' as ext;
 import 'async_built_in.dart';
@@ -34,6 +32,6 @@ abstract class AsyncCallable {
       new AsyncBuiltInCallable(name, arguments, (arguments) {
         var result = callback(arguments);
         if (result is ext.Value) return result as Value;
-        return DelegatingFuture.typed(result as Future);
+        return (result as Future).then((value) => value as Value);
       });
 }
diff --git a/lib/src/extend/functions.dart b/lib/src/extend/functions.dart
index 0a956341c..60280b80b 100644
--- a/lib/src/extend/functions.dart
+++ b/lib/src/extend/functions.dart
@@ -789,8 +789,12 @@ bool _selectorPseudoIsSuperselector(
 /// and that have the given [name].
 Iterable<PseudoSelector> _selectorPseudosNamed(
         CompoundSelector compound, String name) =>
-    DelegatingIterable.typed(compound.components.where((simple) =>
-        simple is PseudoSelector &&
-        simple.isClass &&
-        simple.selector != null &&
-        simple.name == name));
+    // TODO(nweiz): Use whereType() when we only have to support Dart 2 runtime
+    // semantics.
+    compound.components
+        .where((pseudo) =>
+            pseudo is PseudoSelector &&
+            pseudo.isClass &&
+            pseudo.selector != null &&
+            pseudo.name == name)
+        .cast();
diff --git a/lib/src/node.dart b/lib/src/node.dart
index c8e68c632..3f1e99f7d 100644
--- a/lib/src/node.dart
+++ b/lib/src/node.dart
@@ -6,7 +6,6 @@ import 'dart:async';
 import 'dart:js_util';
 import 'dart:typed_data';
 
-import 'package:collection/collection.dart';
 import 'package:dart2_constant/convert.dart' as convert;
 import 'package:js/js.dart';
 import 'package:path/path.dart' as p;
@@ -134,7 +133,7 @@ RenderResult _renderSync(RenderOptions options) {
     if (options.data != null) {
       result = compileString(options.data,
           nodeImporter: _parseImporter(options, start),
-          functions: DelegatingList.typed(_parseFunctions(options)),
+          functions: _parseFunctions(options).cast(),
           indented: isTruthy(options.indentedSyntax),
           style: _parseOutputStyle(options.outputStyle),
           useSpaces: options.indentType != 'tab',
@@ -145,7 +144,7 @@ RenderResult _renderSync(RenderOptions options) {
     } else if (options.file != null) {
       result = compile(file,
           nodeImporter: _parseImporter(options, start),
-          functions: DelegatingList.typed(_parseFunctions(options)),
+          functions: _parseFunctions(options).cast(),
           indented: options.indentedSyntax,
           style: _parseOutputStyle(options.outputStyle),
           useSpaces: options.indentType != 'tab',
@@ -255,7 +254,7 @@ NodeImporter _parseImporter(RenderOptions options, DateTime start) {
   if (options.importer == null) {
     importers = [];
   } else if (options.importer is List) {
-    importers = DelegatingList.typed(options.importer as List);
+    importers = (options.importer as List).cast();
   } else {
     importers = [options.importer as _Importer];
   }
diff --git a/lib/src/value/external/argument_list.dart b/lib/src/value/external/argument_list.dart
index df8eb7c57..c38f7cc6d 100644
--- a/lib/src/value/external/argument_list.dart
+++ b/lib/src/value/external/argument_list.dart
@@ -2,8 +2,6 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'package:collection/collection.dart';
-
 import '../../value.dart' as internal;
 import '../../value.dart' show ListSeparator;
 import 'value.dart';
@@ -21,6 +19,6 @@ abstract class SassArgumentList extends SassList {
 
   factory SassArgumentList(Iterable<Value> contents,
           Map<String, Value> keywords, ListSeparator separator) =>
-      new internal.SassArgumentList(DelegatingIterable.typed(contents),
-          DelegatingMap.typed(keywords), separator);
+      new internal.SassArgumentList(
+          contents.cast(), keywords.cast(), separator);
 }
diff --git a/lib/src/value/external/list.dart b/lib/src/value/external/list.dart
index 1c6b75236..64b36874e 100644
--- a/lib/src/value/external/list.dart
+++ b/lib/src/value/external/list.dart
@@ -2,8 +2,6 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'package:collection/collection.dart';
-
 import '../../value.dart' as internal;
 import '../../value.dart' show ListSeparator;
 import 'value.dart';
@@ -23,6 +21,5 @@ abstract class SassList extends Value {
   /// Returns an empty list with the given [separator] and [brackets].
   factory SassList(Iterable<Value> contents, ListSeparator separator,
           {bool brackets: false}) =>
-      new internal.SassList(DelegatingIterable.typed(contents), separator,
-          brackets: brackets);
+      new internal.SassList(contents.cast(), separator, brackets: brackets);
 }
diff --git a/lib/src/value/external/map.dart b/lib/src/value/external/map.dart
index aec5cb4c2..3fa4776aa 100644
--- a/lib/src/value/external/map.dart
+++ b/lib/src/value/external/map.dart
@@ -2,8 +2,6 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'package:collection/collection.dart';
-
 import '../../value.dart' as internal;
 import 'value.dart';
 
@@ -22,5 +20,5 @@ abstract class SassMap extends Value {
   const factory SassMap.empty() = internal.SassMap.empty;
 
   factory SassMap(Map<Value, Value> contents) =>
-      new internal.SassMap(DelegatingMap.typed(contents));
+      new internal.SassMap(contents.cast());
 }
diff --git a/tool/grind/standalone.dart b/tool/grind/standalone.dart
index 5836d2b33..c38672378 100644
--- a/tool/grind/standalone.dart
+++ b/tool/grind/standalone.dart
@@ -68,7 +68,7 @@ Future _buildPackage(http.Client client, String os, {bool x64: true}) async {
       .firstWhere((file) => os == 'windows'
           ? file.name.endsWith("/bin/dart.exe")
           : file.name.endsWith("/bin/dart"));
-  var executable = DelegatingList.typed<int>(dartExecutable.content as List);
+  var executable = dartExecutable.content as List<int>;
 
   // Use the app snapshot when packaging for the current operating system.
   //