diff --git a/kexdhc.c b/kexdhc.c
index bf875ae..64de7af 100644
--- a/kexdhc.c
+++ b/kexdhc.c
@@ -27,6 +27,7 @@
 
 #include <sys/types.h>
 
+#include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
 #include <signal.h>