diff --git a/schema/mappings.json b/schema/mappings.json
index 9c873fb..9cf5ac3 100644
--- a/schema/mappings.json
+++ b/schema/mappings.json
@@ -68,7 +68,7 @@
     },
     "mtime": {
       "type": "date",
-      "format": "epoch_millis"
+      "format": "epoch_second"
     },
     "size": {
       "type": "long"