diff --git a/common/file_posix.cpp b/common/file_posix.cpp
index 534f576b..233ba0f9 100644
--- a/common/file_posix.cpp
+++ b/common/file_posix.cpp
@@ -1,3 +1,6 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
 #include "file.h"
 
 #include <string.h>