diff --git a/ssh-keygen.c b/ssh-keygen.c
index c607e25..969bd23 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -29,6 +29,7 @@
 # include <paths.h>
 #endif
 #include <pwd.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>