diff --git a/src/core.ts b/src/core.ts
index cafdc71..b66252f 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -29,20 +29,14 @@ unstable_replaceInternalFunction(
     },
 );
 
-const callbackStack = [new Set<() => void>()];
-let callbackPromise: Promise<void> | undefined;
+const callbackStack: Set<() => void>[] = [];
 
 const registerCallback = (callback: () => void) => {
-  const callbacks = callbackStack[callbackStack.length - 1]!;
-  callbacks.add(callback);
-  if (!callbackPromise && callbackStack.length === 1) {
-    callbackPromise = Promise.resolve().then(() => {
-      callbackPromise = undefined;
-      for (const callback of callbacks) {
-        callback();
-      }
-      callbacks.clear();
-    });
+  if (callbackStack.length) {
+    callbackStack[callbackStack.length - 1]!.add(callback);
+  } else {
+    // invoke immediately
+    callback();
   }
 };
 
diff --git a/tests/01_watch.spec.ts b/tests/01_watch.spec.ts
index 040c2be..ca46149 100644
--- a/tests/01_watch.spec.ts
+++ b/tests/01_watch.spec.ts
@@ -37,13 +37,10 @@ describe('watch', () => {
     });
     expect(data).toEqual([0]);
     ++state.nested.count;
-    await new Promise<void>((r) => setTimeout(r));
     expect(data).toEqual([0, 1]);
     ++state.count;
-    await new Promise<void>((r) => setTimeout(r));
     expect(data).toEqual([0, 1]);
     ++state.nested.anotherCount;
-    await new Promise<void>((r) => setTimeout(r));
     expect(data).toEqual([0, 1]);
     unwatch();
   });
@@ -59,16 +56,19 @@ describe('watch with batch', () => {
     expect(data).toEqual([0]);
     batch(() => {
       ++state.count;
+      ++state.count;
     });
-    expect(data).toEqual([0, 1]);
+    expect(data).toEqual([0, 2]);
     batch(() => {
       ++state.count;
+      ++state.count;
     });
-    expect(data).toEqual([0, 1, 2]);
+    expect(data).toEqual([0, 2, 4]);
     unwatch();
     batch(() => {
       ++state.count;
+      ++state.count;
     });
-    expect(data).toEqual([0, 1, 2]);
+    expect(data).toEqual([0, 2, 4]);
   });
 });