diff --git a/sys/amd64/include/stdarg.h b/sys/amd64/include/stdarg.h
index c13137d93efa..60a204ad177f 100644
--- a/sys/amd64/include/stdarg.h
+++ b/sys/amd64/include/stdarg.h
@@ -46,9 +46,12 @@ typedef	__va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#define	__va_copy(dest, src) \
+	__builtin_va_copy((dest), (src))
+
 #if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
-	__builtin_va_copy((dest), (src))
+	__va_copy(dest, src)
 #endif
 
 #define	va_end(ap) \