diff --git a/gss-serv.c b/gss-serv.c
index 296f63a..e8191a8 100644
--- a/gss-serv.c
+++ b/gss-serv.c
@@ -30,6 +30,7 @@
 
 #include <sys/types.h>
 
+#include <stdarg.h>
 #include <string.h>
 #include <unistd.h>