diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c044aa..df9123c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.11.0+4
+
+* Cleanup some ambiguous and some incorrect type signatures.
+
 ## 0.11.0+3
 
 * Improve the speed and memory efficiency of parsing.
diff --git a/lib/parser.dart b/lib/parser.dart
index 6060166..dce31b6 100644
--- a/lib/parser.dart
+++ b/lib/parser.dart
@@ -130,7 +130,7 @@
 
   if (input is String) {
     source = input;
-  } else if (input is List<int>) {
+  } else if (input is List) {
     // TODO(terry): The parse function needs an "encoding" argument and will
     //              default to whatever encoding CSS defaults to.
     //
@@ -145,7 +145,7 @@
     // See encoding helpers at: package:html5lib/lib/src/char_encodings.dart
     // These helpers can decode in different formats given an encoding name
     // (mostly unicode, ascii, windows-1252 which is html5 default encoding).
-    source = new String.fromCharCodes(input);
+    source = new String.fromCharCodes(input as List<int>);
   } else {
     // TODO(terry): Support RandomAccessFile using console.
     throw new ArgumentError("'source' must be a String or "
diff --git a/lib/src/analyzer.dart b/lib/src/analyzer.dart
index 6758a2d..da1a9fa 100644
--- a/lib/src/analyzer.dart
+++ b/lib/src/analyzer.dart
@@ -595,7 +595,7 @@
    * Given a mixin's defined arguments return a cloned mixin defintion that has
    * replaced all defined arguments with user's supplied VarUsages.
    */
-  MixinDefinition transform(List<TreeNode> callArgs) {
+  MixinDefinition transform(List callArgs) {
     // TODO(terry): Handle default arguments and varArgs.
     // Transform mixin with callArgs.
     var index = 0;
diff --git a/lib/src/polyfill.dart b/lib/src/polyfill.dart
index ef3c7b9..95749b9 100644
--- a/lib/src/polyfill.dart
+++ b/lib/src/polyfill.dart
@@ -144,7 +144,7 @@
     } else if (node.defaultValues.any((e) => e is VarUsage)) {
       // Don't have a VarDefinition need to use default values resolve all
       // default values.
-      var terminalDefaults = [];
+      var terminalDefaults = <Expression>[];
       for (var defaultValue in node.defaultValues) {
         terminalDefaults.addAll(resolveUsageTerminal(defaultValue));
       }
@@ -199,7 +199,7 @@
     return result;
   }
 
-  _resolveVarUsage(List<Expressions> expressions, int index,
+  _resolveVarUsage(List<Expression> expressions, int index,
                    VarDefinition def) {
     var defExpressions = (def.expression as Expressions).expressions;
     expressions.replaceRange(index, index + 1, defExpressions);
diff --git a/lib/src/property.dart b/lib/src/property.dart
index 777288a..5219c25 100644
--- a/lib/src/property.dart
+++ b/lib/src/property.dart
@@ -184,7 +184,7 @@
 
   int get argbValue => Color.hexToInt(_argb);
 
-  bool operator ==(Object other) => Color.equal(this, other);
+  bool operator ==(other) => Color.equal(this, other);
 
   String toHexArgbString() => _argb;
 
@@ -198,7 +198,7 @@
     return new Color.hex("${newRgba.toHexArgbString()}");
   }
 
-  static bool equal(ColorBase curr, Object other) {
+  static bool equal(ColorBase curr, other) {
     if (other is Color) {
       Color o = other;
       return o.toHexArgbString() == curr.toHexArgbString();
@@ -601,7 +601,7 @@
     return v1;
   }
 
-  bool operator ==(Object other) => Color.equal(this, other);
+  bool operator ==(other) => Color.equal(this, other);
 
   String get cssExpression {
     if (a == null) {
@@ -763,7 +763,7 @@
    */
   num get alpha => _a;
 
-  bool operator ==(Object other) => Color.equal(this, other);
+  bool operator ==(other) => Color.equal(this, other);
 
   String get cssExpression => (_a == null) ?
       "hsl($hueDegrees,$saturationPercentage,$lightnessPercentage)" :
@@ -1099,7 +1099,7 @@
     return size.toInt() % family[0].hashCode;
   }
 
-  bool operator ==(Object other) {
+  bool operator ==(other) {
     if (other is! Font) return false;
     Font o = other;
     return o.size == size && o.family == family && o.weight == weight &&
diff --git a/lib/src/tree.dart b/lib/src/tree.dart
index 53a5f9f..37d0741 100644
--- a/lib/src/tree.dart
+++ b/lib/src/tree.dart
@@ -1206,11 +1206,10 @@
             lineHeight: lineHeight),
         super(DartStyleExpression.fontStyle, span);
 
-  FontExpression merged(FontExpression newFontExpr) {
-    if (this.isFont && newFontExpr.isFont) {
+  FontExpression merged(DartStyleExpression newFontExpr) {
+    if (newFontExpr is FontExpression && this.isFont && newFontExpr.isFont) {
       return new FontExpression.merge(this, newFontExpr);
     }
-
     return null;
   }
 
@@ -1222,8 +1221,8 @@
   }
 
   FontExpression._merge(FontExpression x, FontExpression y, SourceSpan span)
-      : super(DartStyleExpression.fontStyle, span),
-        font = new Font.merge(x.font, y.font);
+      : font = new Font.merge(x.font, y.font),
+        super(DartStyleExpression.fontStyle, span);
 
   FontExpression clone() =>
     new FontExpression(span, size: font.size, family: font.family,
@@ -1239,13 +1238,6 @@
   BoxExpression(int styleType, SourceSpan span, this.box)
       : super(styleType, span);
 
-  /*
-   * Merges give 2 DartStyleExpression (or derived from DartStyleExpression,
-   * e.g., FontExpression, etc.) will merge if the two expressions are of the
-   * same property name (implies same exact type e.g, FontExpression).
-   */
-  merged(BoxExpression newDartExpr);
-
   visit(VisitorBase visitor) => visitor.visitBoxExpression(this);
 
   String get formattedBoxEdge {
@@ -1272,8 +1264,9 @@
   MarginExpression.boxEdge(SourceSpan span, BoxEdge box)
       : super(DartStyleExpression.marginStyle, span, box);
 
-  merged(MarginExpression newMarginExpr) {
-    if (this.isMargin && newMarginExpr.isMargin) {
+  merged(DartStyleExpression newMarginExpr) {
+    if (newMarginExpr is MarginExpression && this.isMargin &&
+        newMarginExpr.isMargin) {
       return new MarginExpression.merge(this, newMarginExpr);
     }
 
@@ -1307,8 +1300,8 @@
   BorderExpression.boxEdge(SourceSpan span, BoxEdge box)
       : super(DartStyleExpression.borderStyle, span, box);
 
-  merged(BorderExpression newBorderExpr) {
-    if (this.isBorder && newBorderExpr.isBorder) {
+  merged(DartStyleExpression newBorderExpr) {
+    if (newBorderExpr is BorderExpression && this.isBorder && newBorderExpr.isBorder) {
       return new BorderExpression.merge(this, newBorderExpr);
     }
 
@@ -1340,8 +1333,8 @@
   HeightExpression(SourceSpan span, this.height)
       : super(DartStyleExpression.heightStyle, span);
 
-  merged(HeightExpression newHeightExpr) {
-    if (this.isHeight && newHeightExpr.isHeight) {
+  merged(DartStyleExpression newHeightExpr) {
+    if (newHeightExpr is DartStyleExpression && this.isHeight && newHeightExpr.isHeight) {
       return newHeightExpr;
     }
 
@@ -1358,8 +1351,9 @@
   WidthExpression(SourceSpan span, this.width)
       : super(DartStyleExpression.widthStyle, span);
 
-  merged(WidthExpression newWidthExpr) {
-    if (this.isWidth && newWidthExpr.isWidth) {
+  merged(DartStyleExpression newWidthExpr) {
+    if (newWidthExpr is WidthExpression && this.isWidth &&
+        newWidthExpr.isWidth) {
       return newWidthExpr;
     }
 
@@ -1379,8 +1373,9 @@
   PaddingExpression.boxEdge(SourceSpan span, BoxEdge box)
       : super(DartStyleExpression.paddingStyle, span, box);
 
-  merged(PaddingExpression newPaddingExpr) {
-    if (this.isPadding && newPaddingExpr.isPadding) {
+  merged(DartStyleExpression newPaddingExpr) {
+    if (newPaddingExpr is PaddingExpression && this.isPadding &&
+        newPaddingExpr.isPadding) {
       return new PaddingExpression.merge(this, newPaddingExpr);
     }
 
diff --git a/lib/visitor.dart b/lib/visitor.dart
index aac7242..154d235 100644
--- a/lib/visitor.dart
+++ b/lib/visitor.dart
@@ -40,7 +40,7 @@
 
   void visitRuleSet(RuleSet node);
   void visitDeclarationGroup(DeclarationGroup node);
-  void visitMarginGroup(DeclarationGroup node);
+  void visitMarginGroup(MarginGroup node);
   void visitDeclaration(Declaration node);
   void visitVarDefinition(VarDefinition node);
   void visitIncludeMixinAtDeclaration(IncludeMixinAtDeclaration node);
diff --git a/pubspec.yaml b/pubspec.yaml
index 462fde0..7bb6317 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: csslib
-version: 0.11.0+3
+version: 0.11.0+4
 author: Polymer.dart Team <web-ui-dev@dartlang.org>
 description: A library for parsing CSS.
 homepage: https://github.com/dart-lang/csslib