diff --git a/test/time_controller/simulated_time_controller.cc b/test/time_controller/simulated_time_controller.cc
index 10592edaf4..ba5e162cf0 100644
--- a/test/time_controller/simulated_time_controller.cc
+++ b/test/time_controller/simulated_time_controller.cc
@@ -312,18 +312,6 @@ std::unique_ptr<ProcessThread> SimulatedTimeControllerImpl::CreateProcessThread(
   return process_thread;
 }
 
-std::vector<SimulatedSequenceRunner*>
-SimulatedTimeControllerImpl::GetNextReadyRunner(Timestamp current_time) {
-  rtc::CritScope lock(&lock_);
-  std::vector<SimulatedSequenceRunner*> ready;
-  for (auto* runner : runners_) {
-    if (yielded_.find(runner) == yielded_.end() &&
-        runner->GetNextRunTime() <= current_time) {
-      ready.push_back(runner);
-    }
-  }
-  return ready;
-}
 
 void SimulatedTimeControllerImpl::YieldExecution() {
   if (rtc::CurrentThreadId() == thread_id_) {
@@ -352,11 +340,23 @@ void SimulatedTimeControllerImpl::RunReadyRunners() {
   // We repeat until we have no ready left to handle tasks posted by ready
   // runners.
   while (true) {
-    auto ready = GetNextReadyRunner(current_time);
-    if (ready.empty())
-      break;
-    for (auto* runner : ready) {
+    rtc::CritScope lock(&lock_);
+    RTC_DCHECK(ready_runners_.empty());
+    for (auto* runner : runners_) {
+      if (yielded_.find(runner) == yielded_.end() &&
+          runner->GetNextRunTime() <= current_time) {
+        ready_runners_.push_back(runner);
+      }
+    }
+    if (ready_runners_.empty())
+      return;
+    while (!ready_runners_.empty()) {
+      auto* runner = ready_runners_.front();
+      ready_runners_.pop_front();
       runner->UpdateReady(current_time);
+      // Note that the Run function might indirectly cause a call to
+      // Unregister() which will recursively grab |lock_| again to remove items
+      // from |ready_runners_|.
       runner->Run(current_time);
     }
   }
@@ -390,6 +390,7 @@ void SimulatedTimeControllerImpl::Unregister(SimulatedSequenceRunner* runner) {
   rtc::CritScope lock(&lock_);
   bool removed = RemoveByValue(runners_, runner);
   RTC_CHECK(removed);
+  RemoveByValue(ready_runners_, runner);
 }
 
 }  // namespace sim_time_impl
diff --git a/test/time_controller/simulated_time_controller.h b/test/time_controller/simulated_time_controller.h
index 6837643412..b870fa353d 100644
--- a/test/time_controller/simulated_time_controller.h
+++ b/test/time_controller/simulated_time_controller.h
@@ -60,16 +60,17 @@ class SimulatedTimeControllerImpl : public TaskQueueFactory,
   void Unregister(SimulatedSequenceRunner* runner);
 
  private:
-  // Returns runners in |runners_| that are ready for execution.
-  std::vector<SimulatedSequenceRunner*> GetNextReadyRunner(
-      Timestamp current_time) RTC_RUN_ON(thread_checker_);
-
   const rtc::PlatformThreadId thread_id_;
   rtc::ThreadChecker thread_checker_;
   rtc::CriticalSection time_lock_;
   Timestamp current_time_ RTC_GUARDED_BY(time_lock_);
   rtc::CriticalSection lock_;
   std::vector<SimulatedSequenceRunner*> runners_ RTC_GUARDED_BY(lock_);
+  // Used in RunReadyRunners() to keep track of ready runners that are to be
+  // processed in a round robin fashion. the reason it's a member is so that
+  // runners can removed from here by Unregister().
+  std::list<SimulatedSequenceRunner*> ready_runners_ RTC_GUARDED_BY(lock_);
+
   // Task queues on which YieldExecution has been called.
   std::unordered_set<TaskQueueBase*> yielded_ RTC_GUARDED_BY(thread_checker_);
 };