diff --git a/src/thread_pool.cc b/src/thread_pool.cc
index f3319e2..ba53113 100644
--- a/src/thread_pool.cc
+++ b/src/thread_pool.cc
@@ -11,6 +11,7 @@
       name_(name),
       stack_size_(stack_size) {
   const char* reason = "new thread pool worker thread";
+  pthread_attr_t attr;
   CHECK_PTHREAD_CALL(pthread_attr_init, (&attr), reason);
   CHECK_PTHREAD_CALL(pthread_attr_setstacksize, (&attr, stack_size), reason);
   CHECK_PTHREAD_CALL(pthread_create, (&pthread_, &attr, &Callback, this), reason);