diff --git a/app/models/remote_theme.rb b/app/models/remote_theme.rb
index da46d9efd1..d32a7705af 100644
--- a/app/models/remote_theme.rb
+++ b/app/models/remote_theme.rb
@@ -82,7 +82,7 @@ class RemoteTheme < ActiveRecord::Base
     return unless hex
 
     override = hex.downcase
-    if override !~ /^[0-9a-f]{6}$/
+    if override !~ /\A[0-9a-f]{6}\z/
       override = nil
     end
     override