diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 36ab4a7b142..e9370005df7 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3416,7 +3416,7 @@ module ts {
         }
 
         // Return contextual type of parameter or undefined if no contextual type is available
-        function getContextuallyTypedParameterType(parameter: VariableDeclaration): Type {
+        function getContextuallyTypedParameterType(parameter: ParameterDeclaration): Type {
             var func = <FunctionDeclaration>parameter.parent;
             if (func.kind === SyntaxKind.FunctionExpression || func.kind === SyntaxKind.ArrowFunction) {
                 if (isContextSensitiveExpression(func)) {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 78f462230f3..359896c9e4b 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -320,7 +320,7 @@ module ts {
     }
 
     export interface Expression extends Node {
-        contextualType?: Type;
+        contextualType?: Type;  // Used to temporarily assign a contextual type during overload resolution
     }
 
     export interface UnaryExpression extends Expression {