diff --git a/src/util.h b/src/util.h
index 3d2536450..51a694483 100644
--- a/src/util.h
+++ b/src/util.h
@@ -7,6 +7,8 @@
 
 #include "uint256.h"
 
+#include <stdarg.h>
+
 #ifndef WIN32
 #include <sys/types.h>
 #include <sys/time.h>