diff --git a/runtime/thread_pool.cc b/runtime/thread_pool.cc
index d9d2ea3..7aa1641 100644
--- a/runtime/thread_pool.cc
+++ b/runtime/thread_pool.cc
@@ -86,6 +86,8 @@
   Runtime* runtime = Runtime::Current();
   CHECK(runtime->AttachCurrentThread(worker->name_.c_str(), true, nullptr, false));
   worker->thread_ = Thread::Current();
+  // Thread pool workers cannot call into java.
+  worker->thread_->SetCanCallIntoJava(false);
   // Do work until its time to shut down.
   worker->Run();
   runtime->DetachCurrentThread();