diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index ac71a397b6..5f9c8a93dd 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *Rails 3.1.0 (unreleased)*
 
+* json_escape will now return a SafeBuffer string if it receives SafeBuffer string [tenderlove]
+
 * Make sure escape_js returns SafeBuffer string if it receives SafeBuffer string [Prem Sichanugrist]
 
 * Fix escape_js to work correctly with the new SafeBuffer restriction [Paul Gallagher]
diff --git a/actionpack/lib/action_view/template.rb b/actionpack/lib/action_view/template.rb
index b99d24d281..c16588d88d 100644
--- a/actionpack/lib/action_view/template.rb
+++ b/actionpack/lib/action_view/template.rb
@@ -219,6 +219,9 @@ module ActionView
         method_name = self.method_name
 
         if source.encoding_aware?
+          # Avoid performing in-place mutation for SafeBuffer
+          @source = source.to_str if source.html_safe?
+
           # Look for # encoding: *. If we find one, we'll encode the
           # String in that encoding, otherwise, we'll use the
           # default external encoding.
diff --git a/actionpack/test/template/template_test.rb b/actionpack/test/template/template_test.rb
index 81fb34b80f..4d05fee1e3 100644
--- a/actionpack/test/template/template_test.rb
+++ b/actionpack/test/template/template_test.rb
@@ -173,5 +173,10 @@ class TestERBTemplate < ActiveSupport::TestCase
     ensure
       silence_warnings { Encoding.default_external = old }
     end
+
+    def test_render_inline_safebuffer_should_not_raise_error
+      @template = new_template("Hello".html_safe)
+      render
+    end
   end
 end