diff --git a/internal/glfw/glfw/glfw/src/wl_init.c b/internal/glfw/glfw/glfw/src/wl_init.c
index 03776e098..2d423dc9e 100644
--- a/internal/glfw/glfw/glfw/src/wl_init.c
+++ b/internal/glfw/glfw/glfw/src/wl_init.c
@@ -26,6 +26,10 @@
 // It is fine to use C99 in this file because it will not be built with VS
 //========================================================================
 
+#if !defined(_GNU_SOURCE)
+ #define _GNU_SOURCE
+#endif
+
 #define _POSIX_C_SOURCE 200809L
 
 #include "internal.h"
diff --git a/internal/glfw/glfw/glfw/src/wl_window.c b/internal/glfw/glfw/glfw/src/wl_window.c
index cfd54d498..b5e29be73 100644
--- a/internal/glfw/glfw/glfw/src/wl_window.c
+++ b/internal/glfw/glfw/glfw/src/wl_window.c
@@ -26,7 +26,9 @@
 // It is fine to use C99 in this file because it will not be built with VS
 //========================================================================
 
-#define _GNU_SOURCE
+#if !defined(_GNU_SOURCE)
+ #define _GNU_SOURCE
+#endif
 
 #include "internal.h"