diff --git a/configure.in b/configure.in
index 4243e6683..875212e25 100644
--- a/configure.in
+++ b/configure.in
@@ -851,6 +851,7 @@ if test "${has_environ}" != "yes" ; then
      AC_MSG_FAILURE([Could not find 'environ' in unistd.h or available libraries.]) 
 fi
 
+AC_DEFINE([_GNU_SOURCE],[1],[Use GNU C library extensions (e.g. stdndup).])
 
 # set default gcc warnings
 GCC_WARNINGS="-Wall -Wstrict-prototypes -Wformat-security"
diff --git a/src/helper/jim.c b/src/helper/jim.c
index 9d49e8714..5122615d2 100644
--- a/src/helper/jim.c
+++ b/src/helper/jim.c
@@ -53,9 +53,6 @@
 #define JIM_DYNLIB      /* Dynamic library support for UNIX and WIN32 */
 #endif /* JIM_ANSIC */
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE	/* for vasprintf() */
-#endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/target/oocd_trace.c b/src/target/oocd_trace.c
index dc96d13fc..d54766aea 100644
--- a/src/target/oocd_trace.c
+++ b/src/target/oocd_trace.c
@@ -21,11 +21,6 @@
 #include "config.h"
 #endif
 
-// we must define _GNU_SOURCE to get strndup
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-
 #include "oocd_trace.h"
 #include "arm7_9_common.h"