diff --git a/tools/shared.h b/tools/shared.h
index e8075ab5..b87b8659 100644
--- a/tools/shared.h
+++ b/tools/shared.h
@@ -21,7 +21,8 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
-#define _GNU_SOURCE
+#include "config.h"
+
 #include <errno.h>
 #include <dirent.h>
 #include <fcntl.h>