--- a/src/threading.c
+++ b/src/threading.c
@@ -35,7 +35,9 @@ THE SOFTWARE.
 ===============================================================================
 */
 #if defined(__linux__)
+#ifndef _GNU_SOURCE
 # define _GNU_SOURCE /* must be defined before any include */
+#endif
 # ifdef __ANDROID__
 #  include <android/log.h>
 #  define LOG_TAG "LuaLanes"
