diff --git a/src/Makefile.am b/src/Makefile.am
index 0bfeb07..2713e8b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -8,7 +8,7 @@ AM_CPPFLAGS = \
 	-isystem $(top_srcdir)/include/bsd/ \
 	-include $(top_builddir)/config.h \
 	-DLIBBSD_OVERLAY -DLIBBSD_DISABLE_DEPRECATED \
-	-D_GNU_SOURCE -D__REENTRANT
+	-D__REENTRANT
 
 EXTRA_DIST = \
 	libbsd.map \
diff --git a/src/fpurge.c b/src/fpurge.c
index 19d6537..051b625 100644
--- a/src/fpurge.c
+++ b/src/fpurge.c
@@ -24,8 +24,6 @@
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#define _GNU_SOURCE 1
-
 #include <errno.h>
 #include <stdio.h>
 #include <stdio_ext.h>