diff --git a/README.md b/README.md
index 0353a4c675..a0f546a5e8 100644
--- a/README.md
+++ b/README.md
@@ -68,7 +68,7 @@ Mastodon acts as an OAuth2 provider, so 3rd party apps can use the REST and Stre
 ### Requirements
 
 - **PostgreSQL** 12+
-- **Redis** 4+
+- **Redis** 6.2+
 - **Ruby** 3.1+
 - **Node.js** 18+
 
diff --git a/app/controllers/auth/sessions_controller.rb b/app/controllers/auth/sessions_controller.rb
index 6ed7b2baac..962b78de65 100644
--- a/app/controllers/auth/sessions_controller.rb
+++ b/app/controllers/auth/sessions_controller.rb
@@ -183,9 +183,7 @@ class Auth::SessionsController < Devise::SessionsController
     )
 
     # Only send a notification email every hour at most
-    return if redis.get("2fa_failure_notification:#{user.id}").present?
-
-    redis.set("2fa_failure_notification:#{user.id}", '1', ex: 1.hour)
+    return if redis.set("2fa_failure_notification:#{user.id}", '1', ex: 1.hour, get: true).present?
 
     UserMailer.failed_2fa(user, request.remote_ip, request.user_agent, Time.now.utc).deliver_later!
   end