diff --git a/lib/helpers/model/castBulkWrite.js b/lib/helpers/model/castBulkWrite.js
index 0455562f461..8e47afce706 100644
--- a/lib/helpers/model/castBulkWrite.js
+++ b/lib/helpers/model/castBulkWrite.js
@@ -71,7 +71,6 @@ module.exports = function castBulkWrite(originalModel, op, options) {
           overwrite: false,
           upsert: op['updateOne'].upsert
         });
-
       } catch (error) {
         return callback(error, null);
       }
@@ -152,6 +151,7 @@ module.exports = function castBulkWrite(originalModel, op, options) {
         if (error) {
           return callback(error, null);
         }
+        op['replaceOne']['replacement'] = op['replaceOne']['replacement'].toBSON();
         callback(null);
       });
     };