diff --git a/src/Symfony/Component/Routing/Annotation/Route.php b/src/Symfony/Component/Routing/Annotation/Route.php
index 62ad8c8b8624c..e1d621e806064 100644
--- a/src/Symfony/Component/Routing/Annotation/Route.php
+++ b/src/Symfony/Component/Routing/Annotation/Route.php
@@ -31,6 +31,7 @@ class Route
     private $methods = array();
     private $schemes = array();
     private $condition;
+    private $explicitDefaults = false;
 
     /**
      * @param array $data An array of key/value parameters
@@ -161,4 +162,14 @@ public function getCondition()
     {
         return $this->condition;
     }
+
+    public function setExplicitDefaults($explicitDefaults)
+    {
+        $this->explicitDefaults = $explicitDefaults;
+    }
+
+    public function getExplicitDefaults()
+    {
+        return $this->explicitDefaults;
+    }
 }
diff --git a/src/Symfony/Component/Routing/Generator/Dumper/PhpGeneratorDumper.php b/src/Symfony/Component/Routing/Generator/Dumper/PhpGeneratorDumper.php
index 12dd3f28faf0f..363e0806584f6 100644
--- a/src/Symfony/Component/Routing/Generator/Dumper/PhpGeneratorDumper.php
+++ b/src/Symfony/Component/Routing/Generator/Dumper/PhpGeneratorDumper.php
@@ -91,6 +91,7 @@ private function generateDeclaredRoutes()
             $properties[] = $compiledRoute->getTokens();
             $properties[] = $compiledRoute->getHostTokens();
             $properties[] = $route->getSchemes();
+            $properties[] = $route->getExplicitDefaults();
 
             $routes .= sprintf("        '%s' => %s,\n", $name, PhpMatcherDumper::export($properties));
         }
@@ -127,9 +128,9 @@ public function generate($name, $parameters = array(), $referenceType = self::AB
             throw new RouteNotFoundException(sprintf('Unable to generate a URL for the named route "%s" as such route does not exist.', $name));
         }
 
-        list($variables, $defaults, $requirements, $tokens, $hostTokens, $requiredSchemes) = self::$declaredRoutes[$name];
+        list($variables, $defaults, $requirements, $tokens, $hostTokens, $requiredSchemes, $explicitDefaults) = self::$declaredRoutes[$name];
 
-        return $this->doGenerate($variables, $defaults, $requirements, $tokens, $parameters, $name, $referenceType, $hostTokens, $requiredSchemes);
+        return $this->doGenerate($variables, $defaults, $requirements, $tokens, $parameters, $name, $referenceType, $hostTokens, $requiredSchemes, $explicitDefaults);
     }
 EOF;
     }
diff --git a/src/Symfony/Component/Routing/Generator/UrlGenerator.php b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
index 7eea2472f75d8..27396c0a4eb5d 100644
--- a/src/Symfony/Component/Routing/Generator/UrlGenerator.php
+++ b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
@@ -141,7 +141,7 @@ public function generate($name, $parameters = array(), $referenceType = self::AB
      * @throws InvalidParameterException           When a parameter value for a placeholder is not correct because
      *                                             it does not match the requirement
      */
-    protected function doGenerate($variables, $defaults, $requirements, $tokens, $parameters, $name, $referenceType, $hostTokens, array $requiredSchemes = array())
+    protected function doGenerate($variables, $defaults, $requirements, $tokens, $parameters, $name, $referenceType, $hostTokens, array $requiredSchemes = array(), $explicitDefaults = false)
     {
         $variables = array_flip($variables);
         $mergedParams = array_replace($defaults, $this->context->getParameters(), $parameters);
@@ -156,7 +156,7 @@ protected function doGenerate($variables, $defaults, $requirements, $tokens, $pa
         $message = 'Parameter "{parameter}" for route "{route}" must match "{expected}" ("{given}" given) to generate a corresponding URL.';
         foreach ($tokens as $token) {
             if ('variable' === $token[0]) {
-                if (!$optional || !array_key_exists($token[3], $defaults) || null !== $mergedParams[$token[3]] && (string) $mergedParams[$token[3]] !== (string) $defaults[$token[3]]) {
+                if (!$optional || !array_key_exists($token[3], $defaults) || null !== $mergedParams[$token[3]] && ((string) $mergedParams[$token[3]] !== (string) $defaults[$token[3]]) || true === $explicitDefaults)  {
                     // check requirement
                     if (null !== $this->strictRequirements && !preg_match('#^'.$token[2].'$#'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
                         if ($this->strictRequirements) {
diff --git a/src/Symfony/Component/Routing/Loader/XmlFileLoader.php b/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
index 54b0c65c0cd26..d75351595757c 100644
--- a/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
@@ -159,6 +159,7 @@ protected function parseImport(RouteCollection $collection, \DOMElement $node, $
         $schemes = $node->hasAttribute('schemes') ? preg_split('/[\s,\|]++/', $node->getAttribute('schemes'), -1, PREG_SPLIT_NO_EMPTY) : null;
         $methods = $node->hasAttribute('methods') ? preg_split('/[\s,\|]++/', $node->getAttribute('methods'), -1, PREG_SPLIT_NO_EMPTY) : null;
         $trailingSlashOnRoot = $node->hasAttribute('trailing-slash-on-root') ? XmlUtils::phpize($node->getAttribute('trailing-slash-on-root')) : true;
+        $explicitDefaults = $node->hasAttribute('explicit-defaults') ? XmlUtils::phpize($node->getAttribute('explicit-defaults')) : false;
 
         list($defaults, $requirements, $options, $condition, /* $paths */, $prefixes) = $this->parseConfigs($node, $path);
 
@@ -222,6 +223,7 @@ protected function parseImport(RouteCollection $collection, \DOMElement $node, $
                 $subCollection->setMethods($methods);
             }
             $subCollection->addDefaults($defaults);
+            $subCollection->setExplicitDefaults($explicitDefaults);
             $subCollection->addRequirements($requirements);
             $subCollection->addOptions($options);
 
@@ -262,6 +264,7 @@ protected function loadFile($file)
     private function parseConfigs(\DOMElement $node, $path)
     {
         $defaults = array();
+        $explicitDefaults = false;
         $requirements = array();
         $options = array();
         $condition = null;
diff --git a/src/Symfony/Component/Routing/Loader/YamlFileLoader.php b/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
index ca2e313aa4358..34489c0d4c551 100644
--- a/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
@@ -28,7 +28,7 @@
 class YamlFileLoader extends FileLoader
 {
     private static $availableKeys = array(
-        'resource', 'type', 'prefix', 'path', 'host', 'schemes', 'methods', 'defaults', 'requirements', 'options', 'condition', 'controller', 'name_prefix', 'trailing_slash_on_root',
+        'resource', 'type', 'prefix', 'path', 'host', 'schemes', 'methods', 'defaults', 'explicit_defaults', 'requirements', 'options', 'condition', 'controller', 'name_prefix', 'trailing_slash_on_root',
     );
     private $yamlParser;
 
@@ -109,6 +109,7 @@ public function supports($resource, $type = null)
     protected function parseRoute(RouteCollection $collection, $name, array $config, $path)
     {
         $defaults = isset($config['defaults']) ? $config['defaults'] : array();
+        $explicitDefaults = isset($config['explicit_defaults']) ? $config['explicit_defaults'] : false;
         $requirements = isset($config['requirements']) ? $config['requirements'] : array();
         $options = isset($config['options']) ? $config['options'] : array();
         $host = isset($config['host']) ? $config['host'] : '';
@@ -127,7 +128,7 @@ protected function parseRoute(RouteCollection $collection, $name, array $config,
         }
 
         if (\is_array($config['path'])) {
-            $route = new Route('', $defaults, $requirements, $options, $host, $schemes, $methods, $condition);
+            $route = new Route('', $defaults, $requirements, $options, $host, $schemes, $methods, $condition, $explicitDefaults);
 
             foreach ($config['path'] as $locale => $path) {
                 $localizedRoute = clone $route;
@@ -137,7 +138,7 @@ protected function parseRoute(RouteCollection $collection, $name, array $config,
                 $collection->add($name.'.'.$locale, $localizedRoute);
             }
         } else {
-            $route = new Route($config['path'], $defaults, $requirements, $options, $host, $schemes, $methods, $condition);
+            $route = new Route($config['path'], $defaults, $requirements, $options, $host, $schemes, $methods, $condition, $explicitDefaults);
             $collection->add($name, $route);
         }
     }
diff --git a/src/Symfony/Component/Routing/Loader/schema/routing/routing-1.0.xsd b/src/Symfony/Component/Routing/Loader/schema/routing/routing-1.0.xsd
index 1ea4651c3ac2b..c385afa4577d8 100644
--- a/src/Symfony/Component/Routing/Loader/schema/routing/routing-1.0.xsd
+++ b/src/Symfony/Component/Routing/Loader/schema/routing/routing-1.0.xsd
@@ -35,6 +35,7 @@
   <xsd:group name="configs">
     <xsd:choice>
       <xsd:element name="default" nillable="true" type="default" />
+      <xsd:element name="explicit-defaults" nillable="true" type="xsd:boolean" />
       <xsd:element name="requirement" type="element" />
       <xsd:element name="option" type="element" />
       <xsd:element name="condition" type="xsd:string" />
diff --git a/src/Symfony/Component/Routing/Route.php b/src/Symfony/Component/Routing/Route.php
index 1b060a869dd70..eb8b744aa15fa 100644
--- a/src/Symfony/Component/Routing/Route.php
+++ b/src/Symfony/Component/Routing/Route.php
@@ -27,6 +27,7 @@ class Route implements \Serializable
     private $requirements = array();
     private $options = array();
     private $condition = '';
+    private $explicitDefaults = false;
 
     /**
      * @var null|CompiledRoute
@@ -49,8 +50,9 @@ class Route implements \Serializable
      * @param string|string[] $schemes      A required URI scheme or an array of restricted schemes
      * @param string|string[] $methods      A required HTTP method or an array of restricted methods
      * @param string          $condition    A condition that should evaluate to true for the route to match
+     * @param bool            $explicitDefaults
      */
-    public function __construct(string $path, array $defaults = array(), array $requirements = array(), array $options = array(), ?string $host = '', $schemes = array(), $methods = array(), ?string $condition = '')
+    public function __construct(string $path, array $defaults = array(), array $requirements = array(), array $options = array(), ?string $host = '', $schemes = array(), $methods = array(), ?string $condition = '', bool $explicitDefaults = false)
     {
         $this->setPath($path);
         $this->addDefaults($defaults);
@@ -60,6 +62,7 @@ public function __construct(string $path, array $defaults = array(), array $requ
         $this->setSchemes($schemes);
         $this->setMethods($methods);
         $this->setCondition($condition);
+        $this->setExplicitDefaults($explicitDefaults);
     }
 
     /**
@@ -527,6 +530,33 @@ public function setCondition($condition)
         return $this;
     }
 
+    /**
+     * Returns the explicitDefaults.
+     *
+     * @return string The explicitDefaults
+     */
+    public function getExplicitDefaults()
+    {
+        return $this->explicitDefaults;
+    }
+
+    /**
+     * Sets the explicitDefaults.
+     *
+     * This method implements a fluent interface.
+     *
+     * @param string $explicitDefaults The explicitDefaults
+     *
+     * @return $this
+     */
+    public function setExplicitDefaults($explicitDefaults)
+    {
+        $this->explicitDefaults = (bool) $explicitDefaults;
+        $this->compiled = null;
+
+        return $this;
+    }
+
     /**
      * Compiles the route.
      *
diff --git a/src/Symfony/Component/Routing/RouteCollection.php b/src/Symfony/Component/Routing/RouteCollection.php
index 4525404d6d030..02b47d010527b 100644
--- a/src/Symfony/Component/Routing/RouteCollection.php
+++ b/src/Symfony/Component/Routing/RouteCollection.php
@@ -200,6 +200,20 @@ public function setCondition($condition)
         }
     }
 
+    /**
+     * Sets explicit defaults on all routes.
+     *
+     * Existing explicit defaults will be overridden.
+     *
+     * @param bool $explicitDefaults
+     */
+    public function setExplicitDefaults($explicitDefaults)
+    {
+        foreach ($this->routes as $route) {
+            $route->setExplicitDefaults($explicitDefaults);
+        }
+    }
+
     /**
      * Adds defaults to all routes.
      *
diff --git a/src/Symfony/Component/Routing/Tests/Annotation/RouteTest.php b/src/Symfony/Component/Routing/Tests/Annotation/RouteTest.php
index 4d6b2a9c8b45e..6e5c4a04b6f6f 100644
--- a/src/Symfony/Component/Routing/Tests/Annotation/RouteTest.php
+++ b/src/Symfony/Component/Routing/Tests/Annotation/RouteTest.php
@@ -54,6 +54,7 @@ public function getValidParameters()
             array('host', '{locale}.example.com', 'getHost'),
             array('condition', 'context.getMethod() == "GET"', 'getCondition'),
             array('value', array('nl' => '/hier', 'en' => '/here'), 'getLocalizedPaths'),
+            array('explicit_defaults', true, 'getExplicitDefaults'),
         );
     }
 }
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/validresource.php b/src/Symfony/Component/Routing/Tests/Fixtures/validresource.php
index 482c80b29e919..19d61f028fe83 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/validresource.php
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/validresource.php
@@ -6,6 +6,7 @@
 $collection->addDefaults(array(
     'foo' => 123,
 ));
+$collection->setExplicitDefaults(true);
 $collection->addRequirements(array(
     'foo' => '\d+',
 ));
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/validresource.yml b/src/Symfony/Component/Routing/Tests/Fixtures/validresource.yml
index faf2263ae52f4..a2ba1d50020cf 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/validresource.yml
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/validresource.yml
@@ -2,6 +2,7 @@ _blog:
     resource:     validpattern.yml
     prefix:       /{foo}
     defaults:     { 'foo': '123' }
+    explicit_defaults: true
     requirements: { 'foo': '\d+' }
     options:      { 'foo': 'bar' }
     host:         ""
diff --git a/src/Symfony/Component/Routing/Tests/Generator/Dumper/PhpGeneratorDumperTest.php b/src/Symfony/Component/Routing/Tests/Generator/Dumper/PhpGeneratorDumperTest.php
index 311cd12bd7594..5a5f1a042c40f 100644
--- a/src/Symfony/Component/Routing/Tests/Generator/Dumper/PhpGeneratorDumperTest.php
+++ b/src/Symfony/Component/Routing/Tests/Generator/Dumper/PhpGeneratorDumperTest.php
@@ -230,6 +230,19 @@ public function testDumpForRouteWithDefaults()
         $this->assertEquals('/testing', $url);
     }
 
+    public function testDumpForRouteWithExplicitDefaults()
+    {
+        $this->routeCollection->add('Test', (new Route('/testing/{foo}.{_format}', array('foo' => 'bar', '_format' => 'baz')))->setExplicitDefaults(true));
+
+        file_put_contents($this->testTmpFilepath, $this->generatorDumper->dump(array('class' => 'ExplicitDefaultsRoutesUrlGenerator')));
+        include $this->testTmpFilepath;
+
+        $projectUrlGenerator = new \ExplicitDefaultsRoutesUrlGenerator(new RequestContext());
+        $url = $projectUrlGenerator->generate('Test', array());
+
+        $this->assertEquals('/testing/bar.baz', $url);
+    }
+
     public function testDumpWithSchemeRequirement()
     {
         $this->routeCollection->add('Test1', new Route('/testing', array(), array(), array(), '', array('ftp', 'https')));
diff --git a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
index d4bf18ccac929..7e6220aafc18f 100644
--- a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
+++ b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
@@ -291,6 +291,13 @@ public function testNoTrailingSlashForMultipleOptionalParameters()
         $this->assertEquals('/app.php/category/foo', $this->getGenerator($routes)->generate('test', array('slug1' => 'foo')));
     }
 
+    public function testExplicitDefaults()
+    {
+        $routes = $this->getRoutes('test', (new Route('/category/{slug1}'))->setExplicitDefaults(true));
+
+        $this->assertEquals('/app.php/category/foo', $this->getGenerator($routes)->generate('test', array('slug1' => 'foo')));
+    }
+
     public function testWithAnIntegerAsADefaultValue()
     {
         $routes = $this->getRoutes('test', new Route('/{default}', array('default' => 0)));
diff --git a/src/Symfony/Component/Routing/Tests/RouteTest.php b/src/Symfony/Component/Routing/Tests/RouteTest.php
index e28cdaf59315e..2f47b824b874c 100644
--- a/src/Symfony/Component/Routing/Tests/RouteTest.php
+++ b/src/Symfony/Component/Routing/Tests/RouteTest.php
@@ -73,6 +73,12 @@ public function testOption()
         $this->assertTrue($route->hasOption('foo'), '->hasOption() return true if option is set');
     }
 
+    public function testExplicitDefaults()
+    {
+        $route = new Route('/{foo}');
+        $this->assertFalse($route->getExplicitDefaults(), '->getExplicitDefaults() return false by default');
+    }
+
     public function testDefaults()
     {
         $route = new Route('/{foo}');