diff --git a/actionpack/lib/action_dispatch/journey/route.rb b/actionpack/lib/action_dispatch/journey/route.rb
index cc3c7f20cbc4cf08b0fa18af033c8150a7b5a1bf..1ba91d548ecc592cb5216379049008602694b939 100644
--- a/actionpack/lib/action_dispatch/journey/route.rb
+++ b/actionpack/lib/action_dispatch/journey/route.rb
@@ -19,7 +19,7 @@ def initialize(name, app, path, constraints, defaults = {})
         # Unwrap any constraints so we can see what's inside for route generation.
         # This allows the formatter to skip over any mounted applications or redirects
         # that shouldn't be matched when using a url_for without a route name.
-        while app.is_a?(Routing::Mapper::Constraints) do
+        if app.is_a?(Routing::Mapper::Constraints)
           app = app.app
         end
         @dispatcher  = app.is_a?(Routing::RouteSet::Dispatcher)
diff --git a/actionpack/lib/action_dispatch/routing/inspector.rb b/actionpack/lib/action_dispatch/routing/inspector.rb
index 71a0c5e8268e38adbccbf4d19ddb1ee274a8f325..2135b280dae589f6317c6fae3683ac92bd872210 100644
--- a/actionpack/lib/action_dispatch/routing/inspector.rb
+++ b/actionpack/lib/action_dispatch/routing/inspector.rb
@@ -16,7 +16,7 @@ def rack_app(app = self.app)
         @rack_app ||= begin
           class_name = app.class.name.to_s
           if class_name == "ActionDispatch::Routing::Mapper::Constraints"
-            rack_app(app.app)
+            app.app
           elsif ActionDispatch::Routing::Redirect === app || class_name !~ /^ActionDispatch::Routing/
             app
           end
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index f39fd1ea35e5cca286f14f96c11869e0145d2171..b33c5e0dfd855a7784a0225435957022f941d597 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -19,6 +19,15 @@ class Constraints #:nodoc:
         attr_reader :app, :constraints
 
         def initialize(app, constraints, request)
+          # Unwrap Constraints objects.  I don't actually think it's possible
+          # to pass a Constraints object to this constructor, but there were
+          # multiple places that kept testing children of this object.  I
+          # *think* they were just being defensive, but I have no idea.
+          while app.is_a?(self.class)
+            constraints += app.constraints
+            app = app.app
+          end
+
           @app, @constraints, @request = app, constraints, request
         end
 
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 40c767e6852c1ab05cd97a8b1464106df5f4a839..924455bce22eeb2ed9c842b4bc9884dc4b0999f2 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -704,7 +704,7 @@ def recognize_path(path, environment = {})
           old_params = req.path_parameters
           req.path_parameters = old_params.merge params
           dispatcher = route.app
-          while dispatcher.is_a?(Mapper::Constraints) && dispatcher.matches?(env) do
+          if dispatcher.is_a?(Mapper::Constraints) && dispatcher.matches?(env)
             dispatcher = dispatcher.app
           end