diff --git a/lib/letter_avatar.rb b/lib/letter_avatar.rb
index 5105fa2a5..4b51056b8 100644
--- a/lib/letter_avatar.rb
+++ b/lib/letter_avatar.rb
@@ -31,7 +31,7 @@ class LetterAvatar
     end
 
     def generate(username, size, opts = nil)
-      DistributedMutex.synchronize("letter_avatar_#{version}_#{username}_#{size}") do
+      DistributedMutex.synchronize("letter_avatar_#{version}_#{username}") do
         identity = Identity.from_username(username)
 
         cache = true