diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 40cd45e7e4d..2d9f7b44fb9 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7696,7 +7696,7 @@ module ts {
                         checkTypeAssignableTo(caseType, expressionType, clause.expression, /*headMessage*/ undefined);
                     }
                 }
-                checkBlock(clause);
+                forEach(clause.statements, checkSourceElement);
             });
         }
 
@@ -8562,7 +8562,10 @@ module ts {
             if (!(links.flags & NodeCheckFlags.TypeChecked)) {
                 emitExtends = false;
                 potentialThisCollisions.length = 0;
-                checkBody(node);
+
+                forEach(node.statements, checkSourceElement);
+                checkFunctionExpressionBodies(node);
+
                 if (isExternalModule(node)) {
                     var symbol = getExportAssignmentSymbol(node.symbol);
                     if (symbol && symbol.flags & SymbolFlags.Import) {
@@ -8570,11 +8573,16 @@ module ts {
                         getSymbolLinks(symbol).referenced = true;
                     }
                 }
+
                 if (potentialThisCollisions.length) {
                     forEach(potentialThisCollisions, checkIfThisIsCapturedInEnclosingScope);
                     potentialThisCollisions.length = 0;
                 }
-                if (emitExtends) links.flags |= NodeCheckFlags.EmitExtends;
+
+                if (emitExtends) {
+                    links.flags |= NodeCheckFlags.EmitExtends;
+                }
+
                 links.flags |= NodeCheckFlags.TypeChecked;
             }
         }
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 55d5ffd2973..b81c16cad90 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -701,7 +701,7 @@ module ts {
                 write(" {");
                 writeLine();
                 increaseIndent();
-                emitLines((<Block>node.body).statements);
+                emitLines((<ModuleBlock>node.body).statements);
                 decreaseIndent();
                 write("}");
                 writeLine();
@@ -3264,7 +3264,7 @@ module ts {
                     emit(node.body);
                     decreaseIndent();
                     writeLine();
-                    var moduleBlock = <Block>getInnerMostModuleDeclarationFromDottedModule(node).body;
+                    var moduleBlock = <ModuleBlock>getInnerMostModuleDeclarationFromDottedModule(node).body;
                     emitToken(SyntaxKind.CloseBraceToken, moduleBlock.statements.end);
                     scopeEmitEnd();
                 }
@@ -3410,7 +3410,7 @@ module ts {
                 }
             }
 
-            function emitDirectivePrologues(statements: Statement[], startWithNewLine: boolean): number {
+            function emitDirectivePrologues(statements: Node[], startWithNewLine: boolean): number {
                 for (var i = 0; i < statements.length; ++i) {
                     if (isPrologueDirective(statements[i])) {
                         if (startWithNewLine || i > 0) {
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index a1be014acc8..1c7f7035759 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -405,7 +405,7 @@ module ts {
         function traverse(node: Node): T {
             switch (node.kind) {
                 case SyntaxKind.ReturnStatement:
-                    return visitor(node);
+                    return visitor(<ReturnStatement>node);
                 case SyntaxKind.Block:
                 case SyntaxKind.FunctionBlock:
                 case SyntaxKind.IfStatement:
@@ -3591,8 +3591,8 @@ module ts {
             return finishNode(node);
         }
 
-        function parseFunctionDeclaration(fullStart: number, modifiers: ModifiersArray): FunctionLikeDeclaration {
-            var node = <FunctionLikeDeclaration>createNode(SyntaxKind.FunctionDeclaration, fullStart);
+        function parseFunctionDeclaration(fullStart: number, modifiers: ModifiersArray): FunctionDeclaration {
+            var node = <FunctionDeclaration>createNode(SyntaxKind.FunctionDeclaration, fullStart);
             setModifiers(node, modifiers);
             parseExpected(SyntaxKind.FunctionKeyword);
             node.asteriskToken = parseOptionalToken(SyntaxKind.AsteriskToken);
@@ -3857,8 +3857,8 @@ module ts {
             return finishNode(node);
         }
 
-        function parseModuleBody(): Block {
-            var node = <Block>createNode(SyntaxKind.ModuleBlock, scanner.getStartPos());
+        function parseModuleBlock(): ModuleBlock {
+            var node = <ModuleBlock>createNode(SyntaxKind.ModuleBlock, scanner.getStartPos());
             if (parseExpected(SyntaxKind.OpenBraceToken)) {
                 node.statements = parseList(ParsingContext.ModuleElements, /*checkForStrictMode*/ false, parseModuleElement);
                 parseExpected(SyntaxKind.CloseBraceToken);
@@ -3875,7 +3875,7 @@ module ts {
             node.name = parseIdentifier();
             node.body = parseOptional(SyntaxKind.DotToken)
                 ? parseInternalModuleTail(getNodePos(), NodeFlags.Export)
-                : parseModuleBody();
+                : parseModuleBlock();
             return finishNode(node);
         }
 
@@ -3883,7 +3883,7 @@ module ts {
             var node = <ModuleDeclaration>createNode(SyntaxKind.ModuleDeclaration, fullStart);
             node.flags = flags;
             node.name = parseStringLiteral();
-            node.body = parseModuleBody();
+            node.body = parseModuleBlock();
             return finishNode(node);
         }
 
@@ -3950,7 +3950,7 @@ module ts {
             }
         }
 
-        function parseDeclaration(): Statement {
+        function parseDeclaration(): ModuleElement {
             var fullStart = getNodePos();
             var modifiers = parseModifiers();
             if (token === SyntaxKind.ExportKeyword) {
@@ -3961,7 +3961,7 @@ module ts {
             }
 
             var flags = modifiers ? modifiers.flags : 0;
-            var result: Declaration;
+            var result: ModuleElement;
             switch (token) {
                 case SyntaxKind.VarKeyword:
                 case SyntaxKind.LetKeyword:
@@ -4020,7 +4020,7 @@ module ts {
             return parseSourceElementOrModuleElement();
         }
 
-        function parseSourceElementOrModuleElement(): Statement {
+        function parseSourceElementOrModuleElement(): ModuleElement {
             return isDeclarationStart()
                 ? parseDeclaration()
                 : parseStatement();
@@ -4380,7 +4380,7 @@ module ts {
         }
 
         function checkBreakOrContinueStatement(node: BreakOrContinueStatement): boolean {
-            var current = node;
+            var current: Node = node;
             while (current) {
                 if (isAnyFunction(current)) {
                     return grammarErrorOnNode(node, Diagnostics.Jump_target_cannot_cross_function_boundary);
@@ -4765,7 +4765,7 @@ module ts {
 
         function checkModuleDeclarationStatements(node: ModuleDeclaration): boolean {
             if (node.name.kind === SyntaxKind.Identifier && node.body.kind === SyntaxKind.ModuleBlock) {
-                var statements = (<Block>node.body).statements;
+                var statements = (<ModuleBlock>node.body).statements;
                 for (var i = 0, n = statements.length; i < n; i++) {
                     var statement = statements[i];
 
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index b559fee1af1..9a1b2095bc9 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -383,7 +383,7 @@ module ts {
         body?: Block | Expression;
     }
 
-    export interface FunctionDeclaration extends FunctionLikeDeclaration {
+    export interface FunctionDeclaration extends FunctionLikeDeclaration, Statement {
         name: Identifier;
         body?: Block;
     }
@@ -574,7 +574,9 @@ module ts {
         expression: Expression;
     }
 
-    export interface Statement extends Node { }
+    export interface Statement extends Node, ModuleElement {
+        _statementBrand: any;
+    }
 
     export interface Block extends Statement {
         statements: NodeArray<Statement>;
@@ -662,7 +664,11 @@ module ts {
         type?: TypeNode;
     }
 
-    export interface ClassDeclaration extends Declaration {
+    export interface ModuleElement extends Node {
+        _moduleElementBrand: any;
+    }
+
+    export interface ClassDeclaration extends Declaration, ModuleElement {
         name: Identifier;
         typeParameters?: NodeArray<TypeParameterDeclaration>;
         baseType?: TypeReferenceNode;
@@ -670,14 +676,14 @@ module ts {
         members: NodeArray<Node>;
     }
 
-    export interface InterfaceDeclaration extends Declaration {
+    export interface InterfaceDeclaration extends Declaration, ModuleElement {
         name: Identifier;
         typeParameters?: NodeArray<TypeParameterDeclaration>;
         baseTypes?: NodeArray<TypeReferenceNode>;
         members: NodeArray<Node>;
     }
 
-    export interface TypeAliasDeclaration extends Declaration {
+    export interface TypeAliasDeclaration extends Declaration, ModuleElement {
         name: Identifier;
         type: TypeNode;
     }
@@ -689,23 +695,27 @@ module ts {
         initializer?: Expression;
     }
 
-    export interface EnumDeclaration extends Declaration {
+    export interface EnumDeclaration extends Declaration, ModuleElement {
         name: Identifier;
         members: NodeArray<EnumMember>;
     }
 
-    export interface ModuleDeclaration extends Declaration {
+    export interface ModuleDeclaration extends Declaration, ModuleElement {
         name: Identifier | LiteralExpression;
-        body: Block | ModuleDeclaration;
+        body: ModuleBlock | ModuleDeclaration;
     }
 
-    export interface ImportDeclaration extends Declaration {
+    export interface ModuleBlock extends Node, ModuleElement {
+        statements: NodeArray<ModuleElement>
+    }
+
+    export interface ImportDeclaration extends Declaration, ModuleElement {
         name: Identifier;
         entityName?: EntityName;
         externalModuleName?: LiteralExpression;
     }
 
-    export interface ExportAssignment extends Statement {
+    export interface ExportAssignment extends Statement, ModuleElement {
         exportName: Identifier;
     }
 
@@ -717,7 +727,9 @@ module ts {
         hasTrailingNewLine?: boolean;
     }
 
-    export interface SourceFile extends Block {
+    export interface SourceFile extends Node {
+        statements: NodeArray<ModuleElement>;
+
         filename: string;
         text: string;
         getLineAndCharacterFromPosition(position: number): LineAndCharacter;
diff --git a/src/services/services.ts b/src/services/services.ts
index 7ab9c6a41e9..33212de3988 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -3724,7 +3724,7 @@ module ts {
 
                 function aggregate(node: Node): void {
                     if (node.kind === SyntaxKind.BreakStatement || node.kind === SyntaxKind.ContinueStatement) {
-                        statementAccumulator.push(node);
+                        statementAccumulator.push(<BreakOrContinueStatement>node);
                     }
                     // Do not cross function boundaries.
                     else if (!isAnyFunction(node)) {