diff --git a/appletvjs/appletvjs-tests.ts b/appletvjs/appletvjs-tests.ts
index ece6a00dbe..8bdda9c633 100644
--- a/appletvjs/appletvjs-tests.ts
+++ b/appletvjs/appletvjs-tests.ts
@@ -85,13 +85,27 @@ function test_MediaItem() {
 	mediaItem.resumeTime = 0;
 	mediaItem.subtitle = "Subtitle";
 	
-	mediaItem.loadAssetID = function (url, callback) {
+	var loadAssetIDCallback = function (assetID: string, error: string) {
 		//do something
 	};
-	mediaItem.loadCertificate = function (url, callback) {
+	
+	mediaItem.loadAssetID = function (url: string, loadAssetIDCallback: (assetID: string, error: string) => void) {
 		//do something
 	};
-	mediaItem.loadKey = function (url, callback) {
+	
+	var loadCertificateCallback = function (certificate: string, error: string) {
+		//do something
+	};
+	
+	mediaItem.loadCertificate = function (url: string, loadCertificateCallback: (certificate: string, error: string) => void) {
+		//do something
+	};
+	
+	var loadKeyCallback = function (key: string, renewalDate: string, error: string) {
+		//do something
+	};
+	
+	mediaItem.loadKey = function (url: string, loadKeyCallback: (key: string, renewalDate: string, error: string) => void) {
 		//do something
 	};
 }
diff --git a/appletvjs/appletvjs.d.ts b/appletvjs/appletvjs.d.ts
index c26ef5c172..7e3847cd2e 100644
--- a/appletvjs/appletvjs.d.ts
+++ b/appletvjs/appletvjs.d.ts
@@ -1,5 +1,5 @@
 // Type definitions for AppleTVJS
-// Reference: https://developer.apple.com/library/prerelease/tvos/documentation/TVMLJS/Reference/TVJSFrameworkReference/index.html
+// Project: https://developer.apple.com/library/prerelease/tvos/documentation/TVMLJS/Reference/TVJSFrameworkReference/index.html
 // Definitions by: Adam Valverde <https://github.com/brainded>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
@@ -179,13 +179,13 @@ declare module AppleTVJS {
 		resumeTime: number;
 
 		/** A callback function used to load the asset identifier for an item. */
-		loadAssetID: (url, callback) => void;
+		loadAssetID: (url: string, callback: (assetID: string, error: string) => void) => void;
 
 		/** A callback function used to load the security certificate for an item. */
-		loadCertificate: (url, callback) => void;
+		loadCertificate: (url: string, callback: (certificate: string, error: string) => void) => void;
 
 		/** A callback function used to load the security key for an item. */
-		loadKey: (url, callback) => void;
+		loadKey: (url: string, requestData: any, callback: (key: string, renewalDate: string, error: string) => void) => void;
 	}
 
 	interface MenuBarDocument {