diff --git a/activesupport/lib/active_support/core_ext/object/blank.rb b/activesupport/lib/active_support/core_ext/object/blank.rb
index f7efa1e01ac02b785d4c6235fa729dcdbc6f7a91..1b94dee6cc2da83a25236d3a84de6907668896fa 100644
--- a/activesupport/lib/active_support/core_ext/object/blank.rb
+++ b/activesupport/lib/active_support/core_ext/object/blank.rb
@@ -97,8 +97,6 @@ class Hash
 end
 
 class String
-  BLANK_RE = /\A[[:space:]]*\z/
-
   # A string is blank if it's empty or contains whitespaces only:
   #
   #   ''.blank?       # => true