3 files changed, 20 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index 25386af70a..7ff2f11eff 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -6,6 +6,7 @@ require 'active_support/core_ext/string/iterators'
 require 'active_support/core_ext/string/unicode'
 require 'active_support/core_ext/string/xchar'
 require 'active_support/core_ext/string/filters'
+require 'active_support/core_ext/string/behavior'
 
 class String #:nodoc:
   include ActiveSupport::CoreExtensions::String::Access
@@ -15,4 +16,5 @@ class String #:nodoc:
   include ActiveSupport::CoreExtensions::String::StartsEndsWith
   include ActiveSupport::CoreExtensions::String::Iterators
   include ActiveSupport::CoreExtensions::String::Unicode
+  include ActiveSupport::CoreExtensions::String::Behavior
 end
diff --git a/activesupport/lib/active_support/core_ext/string/behavior.rb b/activesupport/lib/active_support/core_ext/string/behavior.rb
new file mode 100644
index 0000000000..a93ca3027f
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/string/behavior.rb
@@ -0,0 +1,13 @@
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module String #:nodoc:
+      module Behavior
+        # Enable more predictable duck-typing on String-like classes. See
+        # Object#acts_like?.
+        def acts_like_string?
+          true
+        end
+      end
+    end
+  end
+end
+\ No newline at end of file
diff --git a/activesupport/lib/active_support/multibyte/chars.rb b/activesupport/lib/active_support/multibyte/chars.rb
index 185d03020c..de2c83f8d1 100644
--- a/activesupport/lib/active_support/multibyte/chars.rb
+++ b/activesupport/lib/active_support/multibyte/chars.rb
@@ -49,6 +49,11 @@ module ActiveSupport::Multibyte #:nodoc:
         false
     end
 
+    # Enable more predictable duck-typing on String-like classes. See Object#acts_like?.
+    def acts_like_string?
+      true
+    end
+
     # Create a new Chars instance.
     def initialize(str)
       @string = str.respond_to?(:string) ? str.string : str