diff --git a/src/Symfony/Component/Routing/Generator/UrlGenerator.php b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
index 6ed70cabdf..e8b02e81c5 100644
--- a/src/Symfony/Component/Routing/Generator/UrlGenerator.php
+++ b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
@@ -140,8 +140,8 @@ class UrlGenerator implements UrlGeneratorInterface, ConfigurableRequirementsInt
         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]]) {
-                    // check requirement
-                    if (null !== $this->strictRequirements && !preg_match('#^'.$token[2].'$#'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
+                    // check requirement (while ignoring look-around patterns)
+                    if (null !== $this->strictRequirements && !preg_match('#^'.preg_replace('/\(\?(?:=|<=|!|<!)((?:[^()\\\\]+|\\\\.|\((?1)\))*)\)/', '', $token[2]).'$#'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
                         if ($this->strictRequirements) {
                             throw new InvalidParameterException(strtr($message, array('{parameter}' => $token[3], '{route}' => $name, '{expected}' => $token[2], '{given}' => $mergedParams[$token[3]])));
                         }
@@ -195,7 +195,8 @@ class UrlGenerator implements UrlGeneratorInterface, ConfigurableRequirementsInt
             $routeHost = '';
             foreach ($hostTokens as $token) {
                 if ('variable' === $token[0]) {
-                    if (null !== $this->strictRequirements && !preg_match('#^'.$token[2].'$#i'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
+                    // check requirement (while ignoring look-around patterns)
+                    if (null !== $this->strictRequirements && !preg_match('#^'.preg_replace('/\(\?(?:=|<=|!|<!)((?:[^()\\\\]+|\\\\.|\((?1)\))*)\)/', '', $token[2]).'$#i'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
                         if ($this->strictRequirements) {
                             throw new InvalidParameterException(strtr($message, array('{parameter}' => $token[3], '{route}' => $name, '{expected}' => $token[2], '{given}' => $mergedParams[$token[3]])));
                         }
diff --git a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
index d4bf18ccac..900d381054 100644
--- a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
+++ b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
@@ -703,6 +703,23 @@ class UrlGeneratorTest extends TestCase
         $this->assertEquals('/app.php/testing#fragment', $url);
     }
 
+    /**
+     * @dataProvider provideLookAroundRequirementsInPath
+     */
+    public function testLookRoundRequirementsInPath($expected, $path, $requirement)
+    {
+        $routes = $this->getRoutes('test', new Route($path, array(), array('foo' => $requirement, 'baz' => '.+?')));
+        $this->assertSame($expected, $this->getGenerator($routes)->generate('test', array('foo' => 'a/b', 'baz' => 'c/d/e')));
+    }
+
+    public function provideLookAroundRequirementsInPath()
+    {
+        yield array('/app.php/a/b/b%28ar/c/d/e', '/{foo}/b(ar/{baz}', '.+(?=/b\\(ar/)');
+        yield array('/app.php/a/b/bar/c/d/e', '/{foo}/bar/{baz}', '.+(?!$)');
+        yield array('/app.php/bar/a/b/bam/c/d/e', '/bar/{foo}/bam/{baz}', '(?<=/bar/).+');
+        yield array('/app.php/bar/a/b/bam/c/d/e', '/bar/{foo}/bam/{baz}', '(?<!^).+');
+    }
+
     protected function getGenerator(RouteCollection $routes, array $parameters = array(), $logger = null)
     {
         $context = new RequestContext('/app.php');