diff --git a/types/express-session/index.d.ts b/types/express-session/index.d.ts
index 24c59db29d..60dedea20a 100644
--- a/types/express-session/index.d.ts
+++ b/types/express-session/index.d.ts
@@ -12,7 +12,7 @@ import node = require('events');
 declare global {
   namespace Express {
     interface Request {
-      session: Session;
+      session?: Session;
       sessionID?: string;
     }