diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 1331f67a78d24468d324952148f4c8c14023d130..003bc1dc2c374a3c6bbf29578857114a6199fd7a 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -119,6 +119,8 @@ def normalize_path(path)
               path
             elsif path.include?(":format") || path.end_with?('/')
               path
+            elsif @options[:format] == true
+              "#{path}.:format"
             else
               "#{path}(.:format)"
             end
diff --git a/actionpack/test/dispatch/mapper_test.rb b/actionpack/test/dispatch/mapper_test.rb
index b6c08ffc33d3c260c4623f68fd9b1a42c8538e27..81f0efb76e4c66cd7860ba941b68b12254b4beb4 100644
--- a/actionpack/test/dispatch/mapper_test.rb
+++ b/actionpack/test/dispatch/mapper_test.rb
@@ -83,6 +83,13 @@ def test_map_wildcard_with_format_false
         assert_equal '/*path', fakeset.conditions.first[:path_info]
         assert_nil fakeset.requirements.first[:path]
       end
+
+      def test_map_wildcard_with_format_true
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+        mapper.match '/*path', :to => 'pages#show', :format => true
+        assert_equal '/*path.:format', fakeset.conditions.first[:path_info]
+      end
     end
   end
 end