diff --git a/ssh-agent.c b/ssh-agent.c
index 6bc1e54..08b0721 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -58,6 +58,7 @@
 # include <paths.h>
 #endif
 #include <signal.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>