diff --git a/src/threadpool.c b/src/threadpool.c
index 10893411..ff64a3ae 100644
--- a/src/threadpool.c
+++ b/src/threadpool.c
@@ -38,7 +38,6 @@ static uv_thread_t* threads;
 static uv_thread_t default_threads[4];
 static QUEUE exit_message;
 static QUEUE wq;
-static volatile int initialized;
 
 
 static void uv__cancelled(struct uv__work* w) {
@@ -105,7 +104,7 @@ static void post(QUEUE* q) {
 UV_DESTRUCTOR(static void cleanup(void)) {
   unsigned int i;
 
-  if (initialized == 0)
+  if (nthreads == 0)
     return;
 
   post(&exit_message);
@@ -122,7 +121,6 @@ UV_DESTRUCTOR(static void cleanup(void)) {
 
   threads = NULL;
   nthreads = 0;
-  initialized = 0;
 }
 #endif
 
@@ -130,6 +128,7 @@ UV_DESTRUCTOR(static void cleanup(void)) {
 static void init_threads(void) {
   unsigned int i;
   const char* val;
+  int spin;
 
   nthreads = ARRAY_SIZE(default_threads);
   val = getenv("UV_THREADPOOL_SIZE");
@@ -161,7 +160,11 @@ static void init_threads(void) {
     if (uv_thread_create(threads + i, worker, NULL))
       abort();
 
-  initialized = 1;
+  do {
+    uv_mutex_lock(&mutex);
+    spin = (idle_threads < nthreads);
+    uv_mutex_unlock(&mutex);
+  } while (spin);
 }