diff --git a/src/sae.c b/src/sae.c
index a4150628..859ec94b 100644
--- a/src/sae.c
+++ b/src/sae.c
@@ -24,6 +24,7 @@
 #include <config.h>
 #endif
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 
 #include <ell/ell.h>