diff --git a/lib/src/callable.dart b/lib/src/callable.dart
index 1ab2d516..6b1d31c1 100644
--- a/lib/src/callable.dart
+++ b/lib/src/callable.dart
@@ -17,11 +17,4 @@ export 'callable/user_defined.dart';
 /// usable in asynchronous contexts. [Callable]s are usable with both the
 /// synchronous and asynchronous `compile()` functions, and as such should be
 /// used in preference to [AsyncCallable]s if possible.
-abstract class Callable extends AsyncCallable {
-  // TODO(nweiz): I'd like to include the argument declaration on this interface
-  // as well, but supporting overloads for built-in callables makes that more
-  // difficult. Ideally, we'd define overloads as purely an implementation
-  // detail of functions, using a helper method. But that would need to
-  // duplicate a lot of the logic in _PerformVisitor, and I can't find an elegant
-  // way to do that.
-}
+abstract class Callable extends AsyncCallable {}
diff --git a/lib/src/extend/extender.dart b/lib/src/extend/extender.dart
index 5e3163eb..a4186c7b 100644
--- a/lib/src/extend/extender.dart
+++ b/lib/src/extend/extender.dart
@@ -28,8 +28,6 @@ class Extender {
   /// extensions.
   final _extensions = <SimpleSelector, Map<ComplexSelector, Extension>>{};
 
-  // TODO: Create a custom PairList class that's more efficient.
-
   /// A map from all simple selectors in extenders to the extensions that those
   /// extenders define.
   final _extensionsByExtender = <SimpleSelector, List<Extension>>{};
diff --git a/lib/src/functions.dart b/lib/src/functions.dart
index eae6dbe0..4b563951 100644
--- a/lib/src/functions.dart
+++ b/lib/src/functions.dart
@@ -225,8 +225,6 @@ final List<BuiltInCallable> coreFunctions = new UnmodifiableListView([
 
   new BuiltInCallable("invert", r"$color, $weight: 50%", (arguments) {
     if (arguments[0] is SassNumber) {
-      // TODO: find some way of ensuring this is stringified using the right
-      // options. We may need to resort to zones.
       return _functionString("invert", arguments.take(1));
     }
 
diff --git a/lib/src/io/vm.dart b/lib/src/io/vm.dart
index 9471170f..565b15aa 100644
--- a/lib/src/io/vm.dart
+++ b/lib/src/io/vm.dart
@@ -26,21 +26,16 @@ String readFile(String path) {
 
   try {
     return UTF8.decode(bytes);
-  } on FormatException {
+  } on FormatException catch (error) {
+    var decodedUntilError =
+        UTF8.decode(bytes.sublist(0, error.offset), allowMalformed: true);
+    var stringOffset = decodedUntilError.length;
+    if (decodedUntilError.endsWith("�")) stringOffset--;
+
     var decoded = UTF8.decode(bytes, allowMalformed: true);
     var sourceFile = new SourceFile.fromString(decoded, url: p.toUri(path));
-
-    // TODO(nweiz): Use [FormatException.offset] instead when
-    // dart-lang/sdk#28293 is fixed.
-    for (var i = 0; i < bytes.length; i++) {
-      if (decoded.codeUnitAt(i) != 0xFFFD) continue;
-      throw new SassException(
-          "Invalid UTF-8.", sourceFile.location(i).pointSpan());
-    }
-
-    // This should be unreachable, but we'll rethrow the original exception just
-    // in case.
-    rethrow;
+    throw new SassException(
+        "Invalid UTF-8.", sourceFile.location(stringOffset).pointSpan());
   }
 }
 
diff --git a/lib/src/parse/selector.dart b/lib/src/parse/selector.dart
index bc398953..8d7649d5 100644
--- a/lib/src/parse/selector.dart
+++ b/lib/src/parse/selector.dart
@@ -135,7 +135,6 @@ class SelectorParser extends Parser {
       components.add(_simpleSelector(allowParent: false));
     }
 
-    // TODO: support "*E" (or talk to Chris about dropping support for hacks).
     return new CompoundSelector(components);
   }
 
diff --git a/lib/src/parse/stylesheet.dart b/lib/src/parse/stylesheet.dart
index 824f786f..ff823dab 100644
--- a/lib/src/parse/stylesheet.dart
+++ b/lib/src/parse/stylesheet.dart
@@ -2008,7 +2008,6 @@ abstract class StylesheetParser extends Parser {
 
         var color = colorsByName[lower];
         if (color != null) {
-          // TODO(nweiz): Avoid copying the color in compressed mode.
           color = new SassColor.rgb(
               color.red, color.green, color.blue, color.alpha);
           setOriginalSpan(color, identifier.span);
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index d4a8433d..1617fd93 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -217,8 +217,6 @@ List<T> longestCommonSubsequence<T>(List<T> list1, List<T> list2,
       list1.length, (_) => new List<T>(list2.length),
       growable: false);
 
-  // TODO(nweiz): Calling [select] here may be expensive. Can we use a memoizing
-  // approach to avoid calling it O(n*m) times in most cases?
   for (var i = 0; i < list1.length; i++) {
     for (var j = 0; j < list2.length; j++) {
       var selection = select(list1[i], list2[j]);
diff --git a/lib/src/visitor/async_evaluate.dart b/lib/src/visitor/async_evaluate.dart
index 13828776..bb2274e5 100644
--- a/lib/src/visitor/async_evaluate.dart
+++ b/lib/src/visitor/async_evaluate.dart
@@ -612,7 +612,6 @@ class _EvaluateVisitor
             .assertInt());
     var to = _addExceptionSpan(node.to.span, () => toNumber.assertInt());
 
-    // TODO: coerce units
     var direction = from > to ? -1 : 1;
     if (!node.isExclusive) to += direction;
     if (from == to) return null;
diff --git a/lib/src/visitor/evaluate.dart b/lib/src/visitor/evaluate.dart
index 0b51614e..fd273661 100644
--- a/lib/src/visitor/evaluate.dart
+++ b/lib/src/visitor/evaluate.dart
@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/synchronize.dart for details.
 //
-// Checksum: cdeeec2634c97638aef571043c0be1e99f22d7d5
+// Checksum: d443af264c677b3e99b5b32511898d92b9b41291
 
 import 'dart:math' as math;
 
@@ -607,7 +607,6 @@ class _EvaluateVisitor
             .assertInt());
     var to = _addExceptionSpan(node.to.span, () => toNumber.assertInt());
 
-    // TODO: coerce units
     var direction = from > to ? -1 : 1;
     if (!node.isExclusive) to += direction;
     if (from == to) return null;
diff --git a/pubspec.yaml b/pubspec.yaml
index 84518446..7c3bb5e9 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,7 +8,7 @@ executables:
   dart-sass: sass
 
 environment:
-  sdk: '>=1.21.0 <2.0.0'
+  sdk: '>=1.22.0 <2.0.0'
 
 dependencies:
   args: "^0.13.0"
diff --git a/tool/grind.dart b/tool/grind.dart
index 02bb29a0..b0bec6ec 100644
--- a/tool/grind.dart
+++ b/tool/grind.dart
@@ -249,7 +249,8 @@ void _ensureBuild() {
 ///
 /// The [client] is used to download the corresponding Dart SDK.
 Future _buildPackage(http.Client client, String os, String architecture) async {
-  // TODO: Compile a single executable that embeds the Dart VM and the snapshot.
+  // TODO: Compile a single executable that embeds the Dart VM and the snapshot
+  // when dart-lang/sdk#27596 is fixed.
   var channel = _isDevSdk ? "dev" : "stable";
   var url = "https://storage.googleapis.com/dart-archive/channels/$channel/"
       "release/$_dartVersion/sdk/dartsdk-$os-$architecture-release.zip";