diff --git a/node-ffi/node-ffi-tests.ts b/node-ffi/node-ffi-tests.ts
index 407036d39..383470503 100644
--- a/node-ffi/node-ffi-tests.ts
+++ b/node-ffi/node-ffi-tests.ts
@@ -28,6 +28,10 @@ import TArray = require('ref-array');
     func(-5);
     func.async(-5, function(err: any, res: any) {});
 }
+{
+    var funcPtr = ffi.Callback('int', [ 'int' ], Math.abs);
+    var func    = ffi.ForeignFunction(funcPtr, 'int', [ 'int' ]);
+}
 {
     var printfPointer = ffi.DynamicLibrary().get('printf');
     var printfGen = ffi.VariadicForeignFunction(printfPointer, 'void', [ 'string' ]);
diff --git a/node-ffi/node-ffi.d.ts b/node-ffi/node-ffi.d.ts
index b2bdd522d..957cf5793 100644
--- a/node-ffi/node-ffi.d.ts
+++ b/node-ffi/node-ffi.d.ts
@@ -140,10 +140,10 @@ declare module "ffi" {
      * accept C callback functions.
      */
     export var Callback: {
-        new (retType: any, argTypes: any[], abi: number, fn: Function): NodeBuffer;
-        new (retType: any, argTypes: any[], fn: Function): NodeBuffer;
-        (retType: any, argTypes: any[], abi: number, fn: Function): NodeBuffer;
-        (retType: any, argTypes: any[], fn: Function): NodeBuffer;
+        new (retType: any, argTypes: any[], abi: number, fn: any): NodeBuffer;
+        new (retType: any, argTypes: any[], fn: any): NodeBuffer;
+        (retType: any, argTypes: any[], abi: number, fn: any): NodeBuffer;
+        (retType: any, argTypes: any[], fn: any): NodeBuffer;
     }
 
     export var ffiType: {
@@ -154,8 +154,8 @@ declare module "ffi" {
         FFI_TYPE: StructType;
     }
 
-    export var CIF: Function;
-    export var CIF_var: Function;
+    export var CIF: (retType: any, types: any[], abi?: any) => NodeBuffer
+    export var CIF_var: (retType: any, types: any[], numFixedArgs: number, abi?: any) => NodeBuffer;
     export var HAS_OBJC: boolean;
     export var FFI_TYPES: {[key: string]: NodeBuffer};
     export var FFI_OK: number;