diff --git a/rack-protection/lib/rack/protection/escaped_params.rb b/rack-protection/lib/rack/protection/escaped_params.rb
index d3e79f8a..3283deca 100644
--- a/rack-protection/lib/rack/protection/escaped_params.rb
+++ b/rack-protection/lib/rack/protection/escaped_params.rb
@@ -66,7 +66,7 @@ module Rack
         when Hash   then escape_hash(object)
         when Array  then object.map { |o| escape(o) }
         when String then escape_string(object)
-        else raise ArgumentError, "cannot escape #{object.inspect}"
+        else nil
         end
       end
 
diff --git a/rack-protection/spec/escaped_params_spec.rb b/rack-protection/spec/escaped_params_spec.rb
index fc39caca..0bd43dc9 100644
--- a/rack-protection/spec/escaped_params_spec.rb
+++ b/rack-protection/spec/escaped_params_spec.rb
@@ -30,5 +30,15 @@ describe Rack::Protection::EscapedParams do
       get '/', :foo => {:bar => "<bar>"}
       body.should == '&lt;bar&gt;'
     end
+
+    it 'leaves cache-breaker params untouched' do
+      mock_app do |env|
+        request = Rack::Request.new(env)
+        [200, {'Content-Type' => 'text/plain'}, ['hi']]
+      end
+
+      get '/?95df8d9bf5237ad08df3115ee74dcb10'
+      body.should == 'hi'
+    end
   end
 end