diff --git a/src/main/ts/safe.ts b/src/main/ts/safe.ts
--- a/src/main/ts/safe.ts
+++ b/src/main/ts/safe.ts
@@ -346,15 +346,6 @@ export function debounce<T extends any[]
 
     fn.cancel = (e?: any) => cancel(e);
 
-    fn.applyAsync = async (thisArg: This, args: T, ct: ICancellation) => {
-        const h = ct.register(cancel);
-        try {
-            await fn.apply(thisArg, args);
-        } finally {
-            h.destroy();
-        }
-    };
-
     return fn;
 }
 
diff --git a/src/test/ts/tests/SafeTests.ts b/src/test/ts/tests/SafeTests.ts
--- a/src/test/ts/tests/SafeTests.ts
+++ b/src/test/ts/tests/SafeTests.ts
@@ -138,15 +138,15 @@ test("debounce tests", async (t, trace) 
     let cancel: (e?: any) => void = notImplemented;
     const ct = new Cancellation(c => cancel = c);
 
-    const d = debounce(async (ct2: ICancellation = Cancellation.none) => {
-        ct2.throwIfRequested();
+    const d = debounce(async () => {
+        ct.throwIfRequested();
         trace.debug("do async increment");
         await fork();
         count++;
         return count;
     }, 0);
 
-    const p = d.applyAsync(null, [ct], ct).then(undefined, () => rejected++);
+    const p = d().then(undefined, () => rejected++);
     cancel();
     await p;