diff --git a/ssh-rsa.c b/ssh-rsa.c
index 28444c1..0e16ff8 100644
--- a/ssh-rsa.c
+++ b/ssh-rsa.c
@@ -22,6 +22,7 @@
 #include <openssl/evp.h>
 #include <openssl/err.h>
 
+#include <stdarg.h>
 #include <string.h>
 
 #include "xmalloc.h"