diff --git a/src/dunst.c b/src/dunst.c
index 20a6415..a933742 100644
--- a/src/dunst.c
+++ b/src/dunst.c
@@ -1,6 +1,5 @@
 /* copyright 2012 - 2013 Sascha Kruse and contributors (see LICENSE for licensing information) */
 
-#define _GNU_SOURCE
 #define XLIB_ILLEGAL_ACCESS
 
 #include "dunst.h"
diff --git a/src/markup.c b/src/markup.c
index 05ef1ff..cd91ff8 100644
--- a/src/markup.c
+++ b/src/markup.c
@@ -1,6 +1,5 @@
 /* copyright 2013 Sascha Kruse and contributors (see LICENSE for licensing information) */
 
-#define _GNU_SOURCE
 #include "markup.h"
 
 #include <assert.h>
diff --git a/src/menu.c b/src/menu.c
index 6c89b92..6bd2940 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -1,6 +1,5 @@
 /* copyright 2013 Sascha Kruse and contributors (see LICENSE for licensing information) */
 
-#define _GNU_SOURCE
 #include "menu.h"
 
 #include <errno.h>
diff --git a/src/notification.c b/src/notification.c
index 4a063ce..abcb19d 100644
--- a/src/notification.c
+++ b/src/notification.c
@@ -1,6 +1,5 @@
 /* copyright 2013 Sascha Kruse and contributors (see LICENSE for licensing information) */
 
-#define _GNU_SOURCE
 #include "notification.h"
 
 #include <assert.h>
diff --git a/src/option_parser.c b/src/option_parser.c
index bbab16c..da85ec5 100644
--- a/src/option_parser.c
+++ b/src/option_parser.c
@@ -1,6 +1,5 @@
 /* copyright 2013 Sascha Kruse and contributors (see LICENSE for licensing information) */
 
-#define _GNU_SOURCE
 #include "option_parser.h"
 
 #include <glib.h>
diff --git a/src/utils.c b/src/utils.c
index 417cfe8..fcd69ae 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1,5 +1,4 @@
 /* copyright 2013 Sascha Kruse and contributors (see LICENSE for licensing information) */
-#define _GNU_SOURCE
 #include "utils.h"
 
 #include <assert.h>