diff --git a/src/x11_window.c b/src/x11_window.c
index a86a8ff1..bf923fe6 100644
--- a/src/x11_window.c
+++ b/src/x11_window.c
@@ -27,9 +27,7 @@
 // It is fine to use C99 in this file because it will not be built with VS
 //========================================================================
 
-#if defined(__linux__)
- #define _GNU_SOURCE
-#endif
+#define _GNU_SOURCE
 
 #include "internal.h"