--- a/ipc/chromium/src/base/platform_thread_posix.cc
+++ b/ipc/chromium/src/base/platform_thread_posix.cc
@@ -119,18 +119,19 @@ bool CreateThread(size_t stack_size, boo
   pthread_attr_init(&attributes);
 
   // Pthreads are joinable by default, so only specify the detached attribute if
   // the thread should be non-joinable.
   if (!joinable) {
     pthread_attr_setdetachstate(&attributes, PTHREAD_CREATE_DETACHED);
   }
 
-  if (stack_size > 0)
-    pthread_attr_setstacksize(&attributes, stack_size);
+  if (stack_size == 0)
+    stack_size = nsIThreadManager::DEFAULT_STACK_SIZE;
+  pthread_attr_setstacksize(&attributes, stack_size);
 
   success = !pthread_create(thread_handle, &attributes, ThreadFunc, delegate);
 
   pthread_attr_destroy(&attributes);
   return success;
 }
 
 }  // anonymous namespace