diff --git a/types/mongoose/index.d.ts b/types/mongoose/index.d.ts
index 90bb04747f..316887ac9c 100644
--- a/types/mongoose/index.d.ts
+++ b/types/mongoose/index.d.ts
@@ -1,4 +1,4 @@
-// Type definitions for Mongoose 5.2.2
+// Type definitions for Mongoose 5.2.3
 // Project: http://mongoosejs.com/
 // Definitions by: horiuchi <https://github.com/horiuchi>
 //                 sindrenm <https://github.com/sindrenm>
@@ -2409,6 +2409,13 @@ declare module "mongoose" {
      */
     read(pref: string, tags?: any[]): this;
 
+    /**
+     * Appends a new $replaceRoot operator to this aggregate pipeline.
+     * Note that the $replaceRoot operator requires field strings to start with '$'. If you are passing in a string Mongoose will prepend '$' if the specified field doesn't start '$'. If you are passing in an object the strings in your expression will not be altered.
+     * @param newRoot field or document which will become the new root document
+     */
+    replaceRoot(newRoot: string | object): this;
+
     /**
      * Appends new custom $sample operator(s) to this aggregate pipeline.
      * @param size number of random documents to pick
diff --git a/types/mongoose/mongoose-tests.ts b/types/mongoose/mongoose-tests.ts
index 02227c681d..da5aa792d8 100644
--- a/types/mongoose/mongoose-tests.ts
+++ b/types/mongoose/mongoose-tests.ts
@@ -1264,6 +1264,8 @@ aggregate.project({
 })
 aggregate.project({ salary_k: { $divide: [ "$salary", 1000 ]}});
 aggregate.read('primaryPreferred').read('pp');
+aggregate.replaceRoot("user");
+aggregate.replaceRoot({x: {$concat: ['$this', '$that']}});
 aggregate.sample(3).sample(3);
 aggregate.skip(10).skip(10);
 aggregate.sort({ field: 'asc', test: -1 });