diff --git a/json_write.pro b/json_write.pro
index e5bfb459c80850ac46ebaf8732e99154bf362927..47ee12d38ae6a5895c65b47125c2588794e59072 100644
--- a/json_write.pro
+++ b/json_write.pro
@@ -1,5 +1,5 @@
 pro json_write, struct, filename
 	openw, unit, filename, /get_lun
-	printf, unit, struct, /implied_print
+	printf, unit, json_serialize(struct, /lower)
 	free_lun, unit
 end