diff --git a/package.json b/package.json
index 348f90990..aaf25567b 100644
--- a/package.json
+++ b/package.json
@@ -84,7 +84,7 @@
     "@types/csurf": "^1.11.0",
     "@types/email-templates": "^8.0.1",
     "@types/express": "^4.17.11",
-    "@types/express-session": "^1.17.0",
+    "@types/express-session": "^1.17.3",
     "@types/lodash": "^4.14.168",
     "@types/node": "^14.14.22",
     "@types/node-schedule": "^1.3.1",
diff --git a/server/types/express.d.ts b/server/types/express.d.ts
index 61f30f0f1..90a880069 100644
--- a/server/types/express.d.ts
+++ b/server/types/express.d.ts
@@ -4,10 +4,6 @@ import type { User } from '../entity/User';
 
 declare global {
   namespace Express {
-    export interface Session {
-      userId?: number;
-    }
-
     export interface Request {
       user?: User;
     }
@@ -19,3 +15,11 @@ declare global {
     next: NextFunction
   ) => Promise<void | NextFunction> | void | NextFunction;
 }
+
+// Declaration merging to apply our own types to SessionData
+// See: (https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/express-session/index.d.ts#L23)
+declare module 'express-session' {
+  export interface SessionData {
+    userId: number;
+  }
+}
diff --git a/yarn.lock b/yarn.lock
index ec835c003..2b328948c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2070,7 +2070,7 @@
     "@types/qs" "*"
     "@types/range-parser" "*"
 
-"@types/express-session@^1.15.5", "@types/express-session@^1.17.0":
+"@types/express-session@^1.15.5":
   version "1.17.0"
   resolved "https://registry.yarnpkg.com/@types/express-session/-/express-session-1.17.0.tgz#770daf81368f6278e3e40dd894e1e52abbdca0cd"
   integrity sha512-OQEHeBFE1UhChVIBhRh9qElHUvTp4BzKKHxMDkGHT7WuYk5eL93hPG7D8YAIkoBSbhNEY0RjreF15zn+U0eLjA==
@@ -2078,6 +2078,13 @@
     "@types/express" "*"
     "@types/node" "*"
 
+"@types/express-session@^1.17.3":
+  version "1.17.3"
+  resolved "https://registry.yarnpkg.com/@types/express-session/-/express-session-1.17.3.tgz#4a37c5c4428b8f922ac8ac1cb4bd9190a4d2b097"
+  integrity sha512-57DnyxiqClXOIjoCgeKCUYfKxBPOlOY/k+l1TPK+7bSwyiPTrS5FIk1Ycql7twk4wO7P5lfOVy6akDGiaMSLfw==
+  dependencies:
+    "@types/express" "*"
+
 "@types/express@*":
   version "4.17.8"
   resolved "https://registry.yarnpkg.com/@types/express/-/express-4.17.8.tgz#3df4293293317e61c60137d273a2e96cd8d5f27a"