diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 80a04129eed..db6f2377a36 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6907,7 +6907,7 @@ namespace ts {
             }
         }
 
-        function isFunctionExpressionOrArrowFunction(node: Node): boolean {
+        function isFunctionExpressionOrArrowFunction(node: Node): node is FunctionExpression {
             return node.kind === SyntaxKind.FunctionExpression || node.kind === SyntaxKind.ArrowFunction;
         }
 
@@ -6926,8 +6926,8 @@ namespace ts {
         function getContextualSignature(node: FunctionExpression | MethodDeclaration): Signature {
             Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node));
             let type = isObjectLiteralMethod(node)
-                ? getContextualTypeForObjectLiteralMethod(<MethodDeclaration>node)
-                : getContextualType(<FunctionExpression>node);
+                ? getContextualTypeForObjectLiteralMethod(node)
+                : getContextualType(node);
             if (!type) {
                 return undefined;
             }
@@ -13656,7 +13656,7 @@ namespace ts {
                     forEach(node.decorators, checkFunctionAndClassExpressionBodies);
                     forEach((<MethodDeclaration>node).parameters, checkFunctionAndClassExpressionBodies);
                     if (isObjectLiteralMethod(node)) {
-                        checkFunctionExpressionOrObjectLiteralMethodBody(<MethodDeclaration>node);
+                        checkFunctionExpressionOrObjectLiteralMethodBody(node);
                     }
                     break;
                 case SyntaxKind.Constructor:
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index ed8b516b7f3..a1f2b53ecff 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -660,7 +660,7 @@ namespace ts {
         return node && node.kind === SyntaxKind.Block && isFunctionLike(node.parent);
     }
 
-    export function isObjectLiteralMethod(node: Node) {
+    export function isObjectLiteralMethod(node: Node): node is MethodDeclaration {
         return node && node.kind === SyntaxKind.MethodDeclaration && node.parent.kind === SyntaxKind.ObjectLiteralExpression;
     }