diff --git a/src/misc/cuserid.c b/src/misc/cuserid.c
index 8ad0b9f3..4e78798d 100644
--- a/src/misc/cuserid.c
+++ b/src/misc/cuserid.c
@@ -1,3 +1,4 @@
+#define _GNU_SOURCE
 #include <pwd.h>
 #include <stdio.h>
 #include <unistd.h>