diff --git a/3rdparty/iaxclient/lib/unixfuncs.c b/3rdparty/iaxclient/lib/unixfuncs.c
index 4b41d7395..ed48f43e3 100644
--- a/3rdparty/iaxclient/lib/unixfuncs.c
+++ b/3rdparty/iaxclient/lib/unixfuncs.c
@@ -13,6 +13,7 @@
  */
 
 #define _BSD_SOURCE
+#define _DEFAULT_SOURCE
 #include <unistd.h>
 #ifndef __USE_POSIX199309
 #define __USE_POSIX199309