diff --git a/include/SDL_config_iphoneos.h b/include/SDL_config_iphoneos.h
index bc3d876fc..f575febc7 100644
--- a/include/SDL_config_iphoneos.h
+++ b/include/SDL_config_iphoneos.h
@@ -44,6 +44,7 @@ typedef unsigned long uintptr_t;
 #define SDL_HAS_64BIT_TYPE	1
 
 #define HAVE_GCC_ATOMICS	1
+#define HAVE_GCC_SYNC_LOCK_TEST_AND_SET	1
 
 #define HAVE_ALLOCA_H		1
 #define HAVE_SYS_TYPES_H	1