diff --git a/xpdevplus.h.in b/xpdevplus.h.in
index be596abe3fcfab7364c11c935c847c4d80f50b76..0afdeebf49cf98cc57744f6080d6fb8adbc2c15c 100644
--- a/xpdevplus.h.in
+++ b/xpdevplus.h.in
@@ -6,7 +6,9 @@
 #define _DEFAULT_SOURCE
 #define _BSD_SOURCE
 #define SPEED_MACROS_ONLY 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE 
+#endif
 #define _FILE_OFFSET_BITS 64
 #endif