diff --git a/activesupport/lib/active_support/core_ext/object/blank.rb b/activesupport/lib/active_support/core_ext/object/blank.rb
index 8a5eb4bc93..f9ff4d9567 100644
--- a/activesupport/lib/active_support/core_ext/object/blank.rb
+++ b/activesupport/lib/active_support/core_ext/object/blank.rb
@@ -90,7 +90,7 @@ class String
   #   '　'.blank?               # => true
   #   ' something here '.blank? # => false
   def blank?
-    self !~ /[^[:space:]]/
+    self =~ /\A[[:space:]]*\z/
   end
 end