diff --git a/src/execution/isolate.cc b/src/execution/isolate.cc
index 45d001ae74..f2b8dd9baa 100644
--- a/src/execution/isolate.cc
+++ b/src/execution/isolate.cc
@@ -3926,18 +3926,15 @@ void Isolate::RemoveCallCompletedCallback(CallCompletedCallback callback) {
 void Isolate::FireCallCompletedCallback(MicrotaskQueue* microtask_queue) {
   if (!thread_local_top()->CallDepthIsZero()) return;
 
-  bool run_microtasks =
-      microtask_queue && microtask_queue->size() &&
-      !microtask_queue->HasMicrotasksSuppressions() &&
+  bool perform_checkpoint =
+      microtask_queue &&
       microtask_queue->microtasks_policy() == v8::MicrotasksPolicy::kAuto;
 
-  if (run_microtasks) {
-    microtask_queue->RunMicrotasks(this);
-  }
+  v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this);
+  if (perform_checkpoint) microtask_queue->PerformCheckpoint(isolate);
 
   if (call_completed_callbacks_.empty()) return;
   // Fire callbacks.  Increase call depth to prevent recursive callbacks.
-  v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this);
   v8::Isolate::SuppressMicrotaskExecutionScope suppress(isolate);
   std::vector<CallCompletedCallback> callbacks(call_completed_callbacks_);
   for (auto& callback : callbacks) {
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 4cbb9eb6ec..8fb1a49d0e 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -19928,21 +19928,25 @@ TEST(SetAutorunMicrotasks) {
   v8::HandleScope scope(env->GetIsolate());
   env->GetIsolate()->AddMicrotasksCompletedCallback(
       &MicrotasksCompletedCallback);
+
+  // If the policy is auto, there's a microtask checkpoint at the end of every
+  // zero-depth API call.
   CompileRun(
       "var ext1Calls = 0;"
       "var ext2Calls = 0;");
   CompileRun("1+1;");
   CHECK_EQ(0, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(0, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(0u, microtasks_completed_callback_count);
+  CHECK_EQ(4u, microtasks_completed_callback_count);
 
   env->GetIsolate()->EnqueueMicrotask(
       Function::New(env.local(), MicrotaskOne).ToLocalChecked());
   CompileRun("1+1;");
   CHECK_EQ(1, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(0, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(1u, microtasks_completed_callback_count);
+  CHECK_EQ(7u, microtasks_completed_callback_count);
 
+  // If the policy is explicit, microtask checkpoints are explicitly invoked.
   env->GetIsolate()->SetMicrotasksPolicy(v8::MicrotasksPolicy::kExplicit);
   env->GetIsolate()->EnqueueMicrotask(
       Function::New(env.local(), MicrotaskOne).ToLocalChecked());
@@ -19951,24 +19955,24 @@ TEST(SetAutorunMicrotasks) {
   CompileRun("1+1;");
   CHECK_EQ(1, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(0, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(1u, microtasks_completed_callback_count);
+  CHECK_EQ(7u, microtasks_completed_callback_count);
 
   env->GetIsolate()->RunMicrotasks();
   CHECK_EQ(2, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(1, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(2u, microtasks_completed_callback_count);
+  CHECK_EQ(8u, microtasks_completed_callback_count);
 
   env->GetIsolate()->EnqueueMicrotask(
       Function::New(env.local(), MicrotaskTwo).ToLocalChecked());
   CompileRun("1+1;");
   CHECK_EQ(2, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(1, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(2u, microtasks_completed_callback_count);
+  CHECK_EQ(8u, microtasks_completed_callback_count);
 
   env->GetIsolate()->RunMicrotasks();
   CHECK_EQ(2, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(2, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(3u, microtasks_completed_callback_count);
+  CHECK_EQ(9u, microtasks_completed_callback_count);
 
   env->GetIsolate()->SetMicrotasksPolicy(v8::MicrotasksPolicy::kAuto);
   env->GetIsolate()->EnqueueMicrotask(
@@ -19976,7 +19980,7 @@ TEST(SetAutorunMicrotasks) {
   CompileRun("1+1;");
   CHECK_EQ(2, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(3, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(4u, microtasks_completed_callback_count);
+  CHECK_EQ(12u, microtasks_completed_callback_count);
 
   env->GetIsolate()->EnqueueMicrotask(
       Function::New(env.local(), MicrotaskTwo).ToLocalChecked());
@@ -19985,13 +19989,13 @@ TEST(SetAutorunMicrotasks) {
     CompileRun("1+1;");
     CHECK_EQ(2, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
     CHECK_EQ(3, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-    CHECK_EQ(4u, microtasks_completed_callback_count);
+    CHECK_EQ(12u, microtasks_completed_callback_count);
   }
 
   CompileRun("1+1;");
   CHECK_EQ(2, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(4, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(5u, microtasks_completed_callback_count);
+  CHECK_EQ(15u, microtasks_completed_callback_count);
 
   env->GetIsolate()->RemoveMicrotasksCompletedCallback(
       &MicrotasksCompletedCallback);
@@ -20000,7 +20004,7 @@ TEST(SetAutorunMicrotasks) {
   CompileRun("1+1;");
   CHECK_EQ(3, CompileRun("ext1Calls")->Int32Value(env.local()).FromJust());
   CHECK_EQ(4, CompileRun("ext2Calls")->Int32Value(env.local()).FromJust());
-  CHECK_EQ(5u, microtasks_completed_callback_count);
+  CHECK_EQ(15u, microtasks_completed_callback_count);
 }