diff --git a/libavformat/img2dec.c b/libavformat/img2dec.c
index 16975792ee..0cbcf4a9dc 100644
--- a/libavformat/img2dec.c
+++ b/libavformat/img2dec.c
@@ -20,6 +20,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#define _DEFAULT_SOURCE
 #define _BSD_SOURCE
 #include <sys/stat.h>
 #include "libavutil/avstring.h"
diff --git a/libavformat/udp.c b/libavformat/udp.c
index d40ea973fe..1bda5af297 100644
--- a/libavformat/udp.c
+++ b/libavformat/udp.c
@@ -24,6 +24,7 @@
  * UDP protocol
  */
 
+#define _DEFAULT_SOURCE
 #define _BSD_SOURCE     /* Needed for using struct ip_mreq with recent glibc */
 
 #include "avformat.h"
diff --git a/libswscale/utils.c b/libswscale/utils.c
index eb1c940371..651b07a0ff 100644
--- a/libswscale/utils.c
+++ b/libswscale/utils.c
@@ -20,6 +20,7 @@
 
 #include "config.h"
 
+#define _DEFAULT_SOURCE
 #define _SVID_SOURCE // needed for MAP_ANONYMOUS
 #define _DARWIN_C_SOURCE // needed for MAP_ANON
 #include <inttypes.h>