Include stdarg.h for the va_copy test
diff --git a/src/cc-compat.h b/src/cc-compat.h
index 37f1ea8..e73cb6d 100644
--- a/src/cc-compat.h
+++ b/src/cc-compat.h
@@ -7,6 +7,8 @@
#ifndef INCLUDE_compat_h__
#define INCLUDE_compat_h__
+#include <stdarg.h>
+
/*
* See if our compiler is known to support flexible array members.
*/