diff --git a/src/api/Methods.ts b/src/api/Methods.ts
index d405aab3f..631769eac 100644
--- a/src/api/Methods.ts
+++ b/src/api/Methods.ts
@@ -67,13 +67,15 @@ export function addIntentListener(intent: string, handler: ContextHandler): List
   return throwIfNoGlobal(() => window.fdc3.addIntentListener(intent, handler));
 }
 
-export function addContextListener(contextTypeOrHandler: string | ContextHandler, handler?: ContextHandler): Listener {
+export function addContextListener(
+  contextTypeOrHandler: string | null | ContextHandler,
+  handler?: ContextHandler
+): Listener {
+  //Handle (deprecated) function signature that allowed contextType argument to be omitted
   if (typeof contextTypeOrHandler !== 'function') {
-    return throwIfNoGlobal(() =>
-      window.fdc3.addContextListener(contextTypeOrHandler as string, handler as ContextHandler)
-    );
+    return throwIfNoGlobal(() => window.fdc3.addContextListener(contextTypeOrHandler, handler as ContextHandler));
   } else {
-    return throwIfNoGlobal(() => window.fdc3.addContextListener(contextTypeOrHandler as ContextHandler));
+    return throwIfNoGlobal(() => window.fdc3.addContextListener(null, contextTypeOrHandler as ContextHandler));
   }
 }
 
diff --git a/test/Methods.test.ts b/test/Methods.test.ts
index f6d8acdaa..6d525f73d 100644
--- a/test/Methods.test.ts
+++ b/test/Methods.test.ts
@@ -184,7 +184,7 @@ describe('test ES6 module', () => {
 
       expect(window.fdc3.addContextListener).toHaveBeenCalledTimes(2);
       expect(window.fdc3.addContextListener).toHaveBeenNthCalledWith(1, type, handler1);
-      expect(window.fdc3.addContextListener).toHaveBeenNthCalledWith(2, handler2);
+      expect(window.fdc3.addContextListener).toHaveBeenNthCalledWith(2, null, handler2);
     });
 
     test('getSystemChannels should delegate to window.fdc3.getSystemChannels', async () => {