diff --git a/src/lxc/string_utils.h b/src/lxc/string_utils.h
index 4065e4e6b..d4e633cc6 100644
--- a/src/lxc/string_utils.h
+++ b/src/lxc/string_utils.h
@@ -20,6 +20,8 @@
 #ifndef __LXC_STRING_UTILS_H
 #define __LXC_STRING_UTILS_H
 
+#include <stdarg.h>
+
 #include "config.h"
 
 #include "initutils.h"