diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8cbfd71..a209ca4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Move `writeConcern` away from top-level option to fix deprecation warning [#422](https://github.com/jdesboeufs/connect-mongo/issues/422)
+
 ## [4.4.1] - 2021-03-23
 
 ### Fixed
diff --git a/package.json b/package.json
index 88d6657..cd69d45 100644
--- a/package.json
+++ b/package.json
@@ -68,7 +68,7 @@
     "@istanbuljs/nyc-config-typescript": "^1.0.1",
     "@types/express": "^4.17.9",
     "@types/express-session": "^1.17.3",
-    "@types/mongodb": "^3.6.3",
+    "@types/mongodb": "^3.6.18",
     "@types/node": "^14.14.20",
     "@types/supertest": "^2.0.10",
     "@typescript-eslint/eslint-plugin": "^4.12.0",
diff --git a/src/lib/MongoStore.ts b/src/lib/MongoStore.ts
index 97b9037..d0bc3e1 100644
--- a/src/lib/MongoStore.ts
+++ b/src/lib/MongoStore.ts
@@ -38,7 +38,7 @@ export type ConnectMongoOptions = {
   // FIXME: remove those any
   serialize?: (a: any) => any
   unserialize?: (a: any) => any
-  writeOperationOptions?: CommonOptions
+  writeOperationOptions?: CommonOptions['writeConcern']
   transformId?: (a: any) => any
   crypto?: CryptoOptions
 }
@@ -61,7 +61,7 @@ type ConcretConnectMongoOptions = {
   // FIXME: remove those any
   serialize?: (a: any) => any
   unserialize?: (a: any) => any
-  writeOperationOptions?: CommonOptions
+  writeOperationOptions?: CommonOptions['writeConcern']
   transformId?: (a: any) => any
   // FIXME: remove above any
   crypto: ConcretCryptoOptions
@@ -225,7 +225,10 @@ export default class MongoStore extends session.Store {
         debug('Creating MongoDB TTL index')
         collection.createIndex(
           { expires: 1 },
-          { expireAfterSeconds: 0, ...this.options.writeOperationOptions }
+          {
+            expireAfterSeconds: 0,
+            writeConcern: this.options.writeOperationOptions,
+          }
         )
         break
       case 'interval':
@@ -233,9 +236,10 @@ export default class MongoStore extends session.Store {
         this.timer = setInterval(
           () =>
             collection.deleteMany(removeQuery(), {
-              ...this.options.writeOperationOptions,
-              w: 0,
-              j: false,
+              writeConcern: {
+                w: 0,
+                j: false,
+              },
             }),
           this.options.autoRemoveInterval * 1000 * 60
         )
@@ -382,7 +386,7 @@ export default class MongoStore extends session.Store {
           { $set: s },
           {
             upsert: true,
-            ...this.options.writeOperationOptions,
+            writeConcern: this.options.writeOperationOptions,
           }
         )
         if (rawResp.upsertedCount > 0) {
@@ -438,7 +442,7 @@ export default class MongoStore extends session.Store {
         const rawResp = await collection.updateOne(
           { _id: this.computeStorageId(sid) },
           { $set: updateFields },
-          this.options.writeOperationOptions
+          { writeConcern: this.options.writeOperationOptions }
         )
         if (rawResp.matchedCount === 0) {
           return callback(new Error('Unable to find the session to touch'))
@@ -499,7 +503,7 @@ export default class MongoStore extends session.Store {
       .then((colleciton) =>
         colleciton.deleteOne(
           { _id: this.computeStorageId(sid) },
-          this.options.writeOperationOptions
+          { writeConcern: this.options.writeOperationOptions }
         )
       )
       .then(() => {
diff --git a/yarn.lock b/yarn.lock
index d78af77..dbee52d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -658,10 +658,10 @@
   resolved "https://registry.yarnpkg.com/@types/minimist/-/minimist-1.2.1.tgz#283f669ff76d7b8260df8ab7a4262cc83d988256"
   integrity sha512-fZQQafSREFyuZcdWFAExYjBiCL7AUCdgsk80iO0q4yihYYdcIiH28CcuPTGFgLOCC8RlW49GSQxdHwZP+I7CNg==
 
-"@types/mongodb@^3.6.3":
-  version "3.6.3"
-  resolved "https://registry.yarnpkg.com/@types/mongodb/-/mongodb-3.6.3.tgz#5655af409d9e32d5d5ae9a653abf3e5f9c83eb7a"
-  integrity sha512-6YNqGP1hk5bjUFaim+QoFFuI61WjHiHE1BNeB41TA00Xd2K7zG4lcWyLLq/XtIp36uMavvS5hoAUJ+1u/GcX2Q==
+"@types/mongodb@^3.6.18":
+  version "3.6.18"
+  resolved "https://registry.yarnpkg.com/@types/mongodb/-/mongodb-3.6.18.tgz#7524c462fc7e3b67892afda8211cd045edee65eb"
+  integrity sha512-JSVFt9p0rTfZ4EgzXmVHUB3ue00xe3CRbQho8nXfImzEDDM4O7I3po1bwbWl/EIbLENxUreZxqLOc8lvcnLVPA==
   dependencies:
     "@types/bson" "*"
     "@types/node" "*"