diff --git a/activemodel/lib/active_model/validations/format.rb b/activemodel/lib/active_model/validations/format.rb
index ff3e95da34..02478dd5b6 100644
--- a/activemodel/lib/active_model/validations/format.rb
+++ b/activemodel/lib/active_model/validations/format.rb
@@ -54,7 +54,7 @@ module ActiveModel
 
     module HelperMethods
       # Validates whether the value of the specified attribute is of the correct
-      # form, going by the regular expression provided.You can require that the
+      # form, going by the regular expression provided. You can require that the
       # attribute matches the regular expression:
       #
       #   class Person < ActiveRecord::Base