diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index cdb3e44b3a..dfe258e463 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -53,6 +53,17 @@ def initialize(env)
       @uuid              = nil
     end
 
+    def check_path_parameters!
+      # If any of the path parameters has an invalid encoding then
+      # raise since it's likely to trigger errors further on.
+      path_parameters.each do |key, value|
+        next unless value.respond_to?(:valid_encoding?)
+        unless value.valid_encoding?
+          raise ActionController::BadRequest, "Invalid parameter: #{key} => #{value}"
+        end
+      end
+    end
+
     def key?(key)
       @env.key?(key)
     end
diff --git a/actionpack/lib/action_dispatch/routing/redirection.rb b/actionpack/lib/action_dispatch/routing/redirection.rb
index c9639bca84..b1b39a5496 100644
--- a/actionpack/lib/action_dispatch/routing/redirection.rb
+++ b/actionpack/lib/action_dispatch/routing/redirection.rb
@@ -22,14 +22,7 @@ def call(env)
       end
 
       def serve(req)
-        # If any of the path parameters has an invalid encoding then
-        # raise since it's likely to trigger errors further on.
-        req.path_parameters.each do |key, value|
-          unless value.valid_encoding?
-            raise ActionController::BadRequest, "Invalid parameter: #{key} => #{value}"
-          end
-        end
-
+        req.check_path_parameters!
         uri = URI.parse(path(req.path_parameters, req))
         
         unless uri.host
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 64a9d1cecd..8777a9cd71 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -30,18 +30,9 @@ def initialize(defaults)
         def dispatcher?; true; end
 
         def serve(req)
+          req.check_path_parameters!
           params = req.path_parameters
 
-          # If any of the path parameters has an invalid encoding then
-          # raise since it's likely to trigger errors further on.
-          params.each do |key, value|
-            next unless value.respond_to?(:valid_encoding?)
-
-            unless value.valid_encoding?
-              raise ActionController::BadRequest, "Invalid parameter: #{key} => #{value}"
-            end
-          end
-
           prepare_params!(params)
 
           # Just raise undefined constant errors if a controller was specified as default.