diff --git a/UPGRADE-5.1.md b/UPGRADE-5.1.md
index 656f0b5d5d..e61de91734 100644
--- a/UPGRADE-5.1.md
+++ b/UPGRADE-5.1.md
@@ -59,6 +59,7 @@ Routing
 
  * Deprecated `RouteCollectionBuilder` in favor of `RoutingConfigurator`.
  * Added argument `$priority` to `RouteCollection::add()`
+ * Deprecated the `RouteCompiler::REGEX_DELIMITER` constant
 
 Yaml
 ----
diff --git a/UPGRADE-6.0.md b/UPGRADE-6.0.md
index 1dfdf1bfda..8df8c5e144 100644
--- a/UPGRADE-6.0.md
+++ b/UPGRADE-6.0.md
@@ -48,3 +48,4 @@ Routing
 
  * Removed `RouteCollectionBuilder`.
  * Added argument `$priority` to `RouteCollection::add()`
+ * Removed the `RouteCompiler::REGEX_DELIMITER` constant
diff --git a/src/Symfony/Component/Routing/CHANGELOG.md b/src/Symfony/Component/Routing/CHANGELOG.md
index 4c04edcb2f..8c712e0e0b 100644
--- a/src/Symfony/Component/Routing/CHANGELOG.md
+++ b/src/Symfony/Component/Routing/CHANGELOG.md
@@ -8,6 +8,7 @@ CHANGELOG
  * deprecated `RouteCollectionBuilder` in favor of `RoutingConfigurator`.
  * added "priority" option to annotated routes
  * added argument `$priority` to `RouteCollection::add()`
+ * deprecated the `RouteCompiler::REGEX_DELIMITER` constant
 
 5.0.0
 -----
diff --git a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
index b286a70495..8800e89854 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
@@ -18,7 +18,6 @@ use Symfony\Component\Config\Resource\FileResource;
 use Symfony\Component\Routing\Annotation\Route as RouteAnnotation;
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
-use Symfony\Component\Routing\RouteCompiler;
 
 /**
  * AnnotationClassLoader loads routing information from a PHP class and its methods.
@@ -206,7 +205,7 @@ abstract class AnnotationClassLoader implements LoaderInterface
             $this->configureRoute($route, $class, $method, $annot);
             if (0 !== $locale) {
                 $route->setDefault('_locale', $locale);
-                $route->setRequirement('_locale', preg_quote($locale, RouteCompiler::REGEX_DELIMITER));
+                $route->setRequirement('_locale', preg_quote($locale));
                 $route->setDefault('_canonical_route', $name);
                 $collection->add($name.'.'.$locale, $route, $priority);
             } else {
diff --git a/src/Symfony/Component/Routing/Loader/Configurator/Traits/LocalizedRouteTrait.php b/src/Symfony/Component/Routing/Loader/Configurator/Traits/LocalizedRouteTrait.php
index a24c256f25..8bd54095f6 100644
--- a/src/Symfony/Component/Routing/Loader/Configurator/Traits/LocalizedRouteTrait.php
+++ b/src/Symfony/Component/Routing/Loader/Configurator/Traits/LocalizedRouteTrait.php
@@ -13,7 +13,6 @@ namespace Symfony\Component\Routing\Loader\Configurator\Traits;
 
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
-use Symfony\Component\Routing\RouteCompiler;
 
 /**
  * @internal
@@ -64,7 +63,7 @@ trait LocalizedRouteTrait
             $routes->add($name.'.'.$locale, $route = $this->createRoute($path));
             $collection->add($namePrefix.$name.'.'.$locale, $route);
             $route->setDefault('_locale', $locale);
-            $route->setRequirement('_locale', preg_quote($locale, RouteCompiler::REGEX_DELIMITER));
+            $route->setRequirement('_locale', preg_quote($locale));
             $route->setDefault('_canonical_route', $namePrefix.$name);
         }
 
diff --git a/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php b/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php
index c5980b1548..caba4e5c62 100644
--- a/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php
+++ b/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php
@@ -93,10 +93,10 @@ trait CompiledUrlMatcherTrait
             }
 
             if ($requiredHost) {
-                if ('#' !== $requiredHost[0] ? $requiredHost !== $host : !preg_match($requiredHost, $host, $hostMatches)) {
+                if ('{' !== $requiredHost[0] ? $requiredHost !== $host : !preg_match($requiredHost, $host, $hostMatches)) {
                     continue;
                 }
-                if ('#' === $requiredHost[0] && $hostMatches) {
+                if ('{' === $requiredHost[0] && $hostMatches) {
                     $hostMatches['_route'] = $ret['_route'];
                     $ret = $this->mergeDefaults($hostMatches, $ret);
                 }
diff --git a/src/Symfony/Component/Routing/RouteCompiler.php b/src/Symfony/Component/Routing/RouteCompiler.php
index 59f3a327e0..2fc92e6879 100644
--- a/src/Symfony/Component/Routing/RouteCompiler.php
+++ b/src/Symfony/Component/Routing/RouteCompiler.php
@@ -19,6 +19,9 @@ namespace Symfony\Component\Routing;
  */
 class RouteCompiler implements RouteCompilerInterface
 {
+    /**
+     * @deprecated since Symfony 5.1, to be removed in 6.0
+     */
     const REGEX_DELIMITER = '#';
 
     /**
@@ -161,8 +164,8 @@ class RouteCompiler implements RouteCompilerInterface
                 $nextSeparator = self::findNextSeparator($followingPattern, $useUtf8);
                 $regexp = sprintf(
                     '[^%s%s]+',
-                    preg_quote($defaultSeparator, self::REGEX_DELIMITER),
-                    $defaultSeparator !== $nextSeparator && '' !== $nextSeparator ? preg_quote($nextSeparator, self::REGEX_DELIMITER) : ''
+                    preg_quote($defaultSeparator),
+                    $defaultSeparator !== $nextSeparator && '' !== $nextSeparator ? preg_quote($nextSeparator) : ''
                 );
                 if (('' !== $nextSeparator && !preg_match('#^\{\w+\}#', $followingPattern)) || '' === $followingPattern) {
                     // When we have a separator, which is disallowed for the variable, we can optimize the regex with a possessive
@@ -217,7 +220,7 @@ class RouteCompiler implements RouteCompilerInterface
         for ($i = 0, $nbToken = \count($tokens); $i < $nbToken; ++$i) {
             $regexp .= self::computeRegexp($tokens, $i, $firstOptional);
         }
-        $regexp = self::REGEX_DELIMITER.'^'.$regexp.'$'.self::REGEX_DELIMITER.'sD'.($isHost ? 'i' : '');
+        $regexp = '{^'.$regexp.'$}sD'.($isHost ? 'i' : '');
 
         // enable Utf8 matching if really required
         if ($needsUtf8) {
@@ -289,14 +292,14 @@ class RouteCompiler implements RouteCompilerInterface
         $token = $tokens[$index];
         if ('text' === $token[0]) {
             // Text tokens
-            return preg_quote($token[1], self::REGEX_DELIMITER);
+            return preg_quote($token[1]);
         } else {
             // Variable tokens
             if (0 === $index && 0 === $firstOptional) {
                 // When the only token is an optional variable token, the separator is required
-                return sprintf('%s(?P<%s>%s)?', preg_quote($token[1], self::REGEX_DELIMITER), $token[3], $token[2]);
+                return sprintf('%s(?P<%s>%s)?', preg_quote($token[1]), $token[3], $token[2]);
             } else {
-                $regexp = sprintf('%s(?P<%s>%s)', preg_quote($token[1], self::REGEX_DELIMITER), $token[3], $token[2]);
+                $regexp = sprintf('%s(?P<%s>%s)', preg_quote($token[1]), $token[3], $token[2]);
                 if ($index >= $firstOptional) {
                     // Enclose each optional token in a subpattern to make it optional.
                     // "?:" means it is non-capturing, i.e. the portion of the subject string that
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher1.php b/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher1.php
index 7811f150a8..b96a267023 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher1.php
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher1.php
@@ -22,8 +22,8 @@ return [
         '/c2/route3' => [[['_route' => 'route3'], 'b.example.com', null, null, false, false, null]],
         '/route5' => [[['_route' => 'route5'], 'c.example.com', null, null, false, false, null]],
         '/route6' => [[['_route' => 'route6'], null, null, null, false, false, null]],
-        '/route11' => [[['_route' => 'route11'], '#^(?P<var1>[^\\.]++)\\.example\\.com$#sDi', null, null, false, false, null]],
-        '/route12' => [[['_route' => 'route12', 'var1' => 'val'], '#^(?P<var1>[^\\.]++)\\.example\\.com$#sDi', null, null, false, false, null]],
+        '/route11' => [[['_route' => 'route11'], '{^(?P<var1>[^\\.]++)\\.example\\.com$}sDi', null, null, false, false, null]],
+        '/route12' => [[['_route' => 'route12', 'var1' => 'val'], '{^(?P<var1>[^\\.]++)\\.example\\.com$}sDi', null, null, false, false, null]],
         '/route17' => [[['_route' => 'route17'], null, null, null, false, false, null]],
     ],
     [ // $regexpList
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher2.php b/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher2.php
index 13629954a8..f675aca43b 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher2.php
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher2.php
@@ -22,8 +22,8 @@ return [
         '/c2/route3' => [[['_route' => 'route3'], 'b.example.com', null, null, false, false, null]],
         '/route5' => [[['_route' => 'route5'], 'c.example.com', null, null, false, false, null]],
         '/route6' => [[['_route' => 'route6'], null, null, null, false, false, null]],
-        '/route11' => [[['_route' => 'route11'], '#^(?P<var1>[^\\.]++)\\.example\\.com$#sDi', null, null, false, false, null]],
-        '/route12' => [[['_route' => 'route12', 'var1' => 'val'], '#^(?P<var1>[^\\.]++)\\.example\\.com$#sDi', null, null, false, false, null]],
+        '/route11' => [[['_route' => 'route11'], '{^(?P<var1>[^\\.]++)\\.example\\.com$}sDi', null, null, false, false, null]],
+        '/route12' => [[['_route' => 'route12', 'var1' => 'val'], '{^(?P<var1>[^\\.]++)\\.example\\.com$}sDi', null, null, false, false, null]],
         '/route17' => [[['_route' => 'route17'], null, null, null, false, false, null]],
         '/secure' => [[['_route' => 'secure'], null, null, ['https' => 0], false, false, null]],
         '/nonsecure' => [[['_route' => 'nonsecure'], null, null, ['http' => 0], false, false, null]],
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher9.php b/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher9.php
index da1c8a706f..5103529d61 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher9.php
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/dumper/compiled_url_matcher9.php
@@ -9,8 +9,8 @@ return [
     true, // $matchHost
     [ // $staticRoutes
         '/' => [
-            [['_route' => 'a'], '#^(?P<d>[^\\.]++)\\.e\\.c\\.b\\.a$#sDi', null, null, false, false, null],
-            [['_route' => 'c'], '#^(?P<e>[^\\.]++)\\.e\\.c\\.b\\.a$#sDi', null, null, false, false, null],
+            [['_route' => 'a'], '{^(?P<d>[^\\.]++)\\.e\\.c\\.b\\.a$}sDi', null, null, false, false, null],
+            [['_route' => 'c'], '{^(?P<e>[^\\.]++)\\.e\\.c\\.b\\.a$}sDi', null, null, false, false, null],
             [['_route' => 'b'], 'd.c.b.a', null, null, false, false, null],
         ],
     ],
diff --git a/src/Symfony/Component/Routing/Tests/RouteCompilerTest.php b/src/Symfony/Component/Routing/Tests/RouteCompilerTest.php
index 5729d4caa5..85d3908aab 100644
--- a/src/Symfony/Component/Routing/Tests/RouteCompilerTest.php
+++ b/src/Symfony/Component/Routing/Tests/RouteCompilerTest.php
@@ -38,7 +38,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Static route',
                 ['/foo'],
-                '/foo', '#^/foo$#sD', [], [
+                '/foo', '{^/foo$}sD', [], [
                     ['text', '/foo'],
                 ],
             ],
@@ -46,7 +46,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a variable',
                 ['/foo/{bar}'],
-                '/foo', '#^/foo/(?P<bar>[^/]++)$#sD', ['bar'], [
+                '/foo', '{^/foo/(?P<bar>[^/]++)$}sD', ['bar'], [
                     ['variable', '/', '[^/]++', 'bar'],
                     ['text', '/foo'],
                 ],
@@ -55,7 +55,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a variable that has a default value',
                 ['/foo/{bar}', ['bar' => 'bar']],
-                '/foo', '#^/foo(?:/(?P<bar>[^/]++))?$#sD', ['bar'], [
+                '/foo', '{^/foo(?:/(?P<bar>[^/]++))?$}sD', ['bar'], [
                     ['variable', '/', '[^/]++', 'bar'],
                     ['text', '/foo'],
                 ],
@@ -64,7 +64,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with several variables',
                 ['/foo/{bar}/{foobar}'],
-                '/foo', '#^/foo/(?P<bar>[^/]++)/(?P<foobar>[^/]++)$#sD', ['bar', 'foobar'], [
+                '/foo', '{^/foo/(?P<bar>[^/]++)/(?P<foobar>[^/]++)$}sD', ['bar', 'foobar'], [
                     ['variable', '/', '[^/]++', 'foobar'],
                     ['variable', '/', '[^/]++', 'bar'],
                     ['text', '/foo'],
@@ -74,7 +74,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with several variables that have default values',
                 ['/foo/{bar}/{foobar}', ['bar' => 'bar', 'foobar' => '']],
-                '/foo', '#^/foo(?:/(?P<bar>[^/]++)(?:/(?P<foobar>[^/]++))?)?$#sD', ['bar', 'foobar'], [
+                '/foo', '{^/foo(?:/(?P<bar>[^/]++)(?:/(?P<foobar>[^/]++))?)?$}sD', ['bar', 'foobar'], [
                     ['variable', '/', '[^/]++', 'foobar'],
                     ['variable', '/', '[^/]++', 'bar'],
                     ['text', '/foo'],
@@ -84,7 +84,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with several variables but some of them have no default values',
                 ['/foo/{bar}/{foobar}', ['bar' => 'bar']],
-                '/foo', '#^/foo/(?P<bar>[^/]++)/(?P<foobar>[^/]++)$#sD', ['bar', 'foobar'], [
+                '/foo', '{^/foo/(?P<bar>[^/]++)/(?P<foobar>[^/]++)$}sD', ['bar', 'foobar'], [
                     ['variable', '/', '[^/]++', 'foobar'],
                     ['variable', '/', '[^/]++', 'bar'],
                     ['text', '/foo'],
@@ -94,7 +94,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with an optional variable as the first segment',
                 ['/{bar}', ['bar' => 'bar']],
-                '', '#^/(?P<bar>[^/]++)?$#sD', ['bar'], [
+                '', '{^/(?P<bar>[^/]++)?$}sD', ['bar'], [
                     ['variable', '/', '[^/]++', 'bar'],
                 ],
             ],
@@ -102,7 +102,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a requirement of 0',
                 ['/{bar}', ['bar' => null], ['bar' => '0']],
-                '', '#^/(?P<bar>0)?$#sD', ['bar'], [
+                '', '{^/(?P<bar>0)?$}sD', ['bar'], [
                     ['variable', '/', '0', 'bar'],
                 ],
             ],
@@ -110,7 +110,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with an optional variable as the first segment with requirements',
                 ['/{bar}', ['bar' => 'bar'], ['bar' => '(foo|bar)']],
-                '', '#^/(?P<bar>(?:foo|bar))?$#sD', ['bar'], [
+                '', '{^/(?P<bar>(?:foo|bar))?$}sD', ['bar'], [
                     ['variable', '/', '(?:foo|bar)', 'bar'],
                 ],
             ],
@@ -118,7 +118,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with only optional variables',
                 ['/{foo}/{bar}', ['foo' => 'foo', 'bar' => 'bar']],
-                '', '#^/(?P<foo>[^/]++)?(?:/(?P<bar>[^/]++))?$#sD', ['foo', 'bar'], [
+                '', '{^/(?P<foo>[^/]++)?(?:/(?P<bar>[^/]++))?$}sD', ['foo', 'bar'], [
                     ['variable', '/', '[^/]++', 'bar'],
                     ['variable', '/', '[^/]++', 'foo'],
                 ],
@@ -127,7 +127,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a variable in last position',
                 ['/foo-{bar}'],
-                '/foo-', '#^/foo\-(?P<bar>[^/]++)$#sD', ['bar'], [
+                '/foo-', '{^/foo\-(?P<bar>[^/]++)$}sD', ['bar'], [
                     ['variable', '-', '[^/]++', 'bar'],
                     ['text', '/foo'],
                 ],
@@ -136,7 +136,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with nested placeholders',
                 ['/{static{var}static}'],
-                '/{static', '#^/\{static(?P<var>[^/]+)static\}$#sD', ['var'], [
+                '/{static', '{^/\{static(?P<var>[^/]+)static\}$}sD', ['var'], [
                     ['text', 'static}'],
                     ['variable', '', '[^/]+', 'var'],
                     ['text', '/{static'],
@@ -146,7 +146,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route without separator between variables',
                 ['/{w}{x}{y}{z}.{_format}', ['z' => 'default-z', '_format' => 'html'], ['y' => '(y|Y)']],
-                '', '#^/(?P<w>[^/\.]+)(?P<x>[^/\.]+)(?P<y>(?:y|Y))(?:(?P<z>[^/\.]++)(?:\.(?P<_format>[^/]++))?)?$#sD', ['w', 'x', 'y', 'z', '_format'], [
+                '', '{^/(?P<w>[^/\.]+)(?P<x>[^/\.]+)(?P<y>(?:y|Y))(?:(?P<z>[^/\.]++)(?:\.(?P<_format>[^/]++))?)?$}sD', ['w', 'x', 'y', 'z', '_format'], [
                     ['variable', '.', '[^/]++', '_format'],
                     ['variable', '', '[^/\.]++', 'z'],
                     ['variable', '', '(?:y|Y)', 'y'],
@@ -158,7 +158,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a format',
                 ['/foo/{bar}.{_format}'],
-                '/foo', '#^/foo/(?P<bar>[^/\.]++)\.(?P<_format>[^/]++)$#sD', ['bar', '_format'], [
+                '/foo', '{^/foo/(?P<bar>[^/\.]++)\.(?P<_format>[^/]++)$}sD', ['bar', '_format'], [
                     ['variable', '.', '[^/]++', '_format'],
                     ['variable', '/', '[^/\.]++', 'bar'],
                     ['text', '/foo'],
@@ -168,7 +168,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Static non UTF-8 route',
                 ["/fo\xE9"],
-                "/fo\xE9", "#^/fo\xE9$#sD", [], [
+                "/fo\xE9", "{^/fo\xE9$}sD", [], [
                     ['text', "/fo\xE9"],
                 ],
             ],
@@ -176,7 +176,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with an explicit UTF-8 requirement',
                 ['/{bar}', ['bar' => null], ['bar' => '.'], ['utf8' => true]],
-                '', '#^/(?P<bar>.)?$#sDu', ['bar'], [
+                '', '{^/(?P<bar>.)?$}sDu', ['bar'], [
                     ['variable', '/', '.', 'bar', true],
                 ],
             ],
@@ -205,7 +205,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Static UTF-8 route',
                 ['/foé'],
-                '/foé', '#^/foé$#sDu', [], [
+                '/foé', '{^/foé$}sDu', [], [
                     ['text', '/foé'],
                 ],
                 'patterns',
@@ -214,7 +214,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with an implicit UTF-8 requirement',
                 ['/{bar}', ['bar' => null], ['bar' => 'é']],
-                '', '#^/(?P<bar>é)?$#sDu', ['bar'], [
+                '', '{^/(?P<bar>é)?$}sDu', ['bar'], [
                     ['variable', '/', 'é', 'bar', true],
                 ],
                 'requirements',
@@ -223,7 +223,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a UTF-8 class requirement',
                 ['/{bar}', ['bar' => null], ['bar' => '\pM']],
-                '', '#^/(?P<bar>\pM)?$#sDu', ['bar'], [
+                '', '{^/(?P<bar>\pM)?$}sDu', ['bar'], [
                     ['variable', '/', '\pM', 'bar', true],
                 ],
                 'requirements',
@@ -232,7 +232,7 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with a UTF-8 separator',
                 ['/foo/{bar}§{_format}', [], [], ['compiler_class' => Utf8RouteCompiler::class]],
-                '/foo', '#^/foo/(?P<bar>[^/§]++)§(?P<_format>[^/]++)$#sDu', ['bar', '_format'], [
+                '/foo', '{^/foo/(?P<bar>[^/§]++)§(?P<_format>[^/]++)$}sDu', ['bar', '_format'], [
                     ['variable', '§', '[^/]++', '_format', true],
                     ['variable', '/', '[^/§]++', 'bar', true],
                     ['text', '/foo'],
@@ -318,21 +318,21 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with host pattern',
                 ['/hello', [], [], [], 'www.example.com'],
-                '/hello', '#^/hello$#sD', [], [], [
+                '/hello', '{^/hello$}sD', [], [], [
                     ['text', '/hello'],
                 ],
-                '#^www\.example\.com$#sDi', [], [
+                '{^www\.example\.com$}sDi', [], [
                     ['text', 'www.example.com'],
                 ],
             ],
             [
                 'Route with host pattern and some variables',
                 ['/hello/{name}', [], [], [], 'www.example.{tld}'],
-                '/hello', '#^/hello/(?P<name>[^/]++)$#sD', ['tld', 'name'], ['name'], [
+                '/hello', '{^/hello/(?P<name>[^/]++)$}sD', ['tld', 'name'], ['name'], [
                     ['variable', '/', '[^/]++', 'name'],
                     ['text', '/hello'],
                 ],
-                '#^www\.example\.(?P<tld>[^\.]++)$#sDi', ['tld'], [
+                '{^www\.example\.(?P<tld>[^\.]++)$}sDi', ['tld'], [
                     ['variable', '.', '[^\.]++', 'tld'],
                     ['text', 'www.example'],
                 ],
@@ -340,10 +340,10 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with variable at beginning of host',
                 ['/hello', [], [], [], '{locale}.example.{tld}'],
-                '/hello', '#^/hello$#sD', ['locale', 'tld'], [], [
+                '/hello', '{^/hello$}sD', ['locale', 'tld'], [], [
                     ['text', '/hello'],
                 ],
-                '#^(?P<locale>[^\.]++)\.example\.(?P<tld>[^\.]++)$#sDi', ['locale', 'tld'], [
+                '{^(?P<locale>[^\.]++)\.example\.(?P<tld>[^\.]++)$}sDi', ['locale', 'tld'], [
                     ['variable', '.', '[^\.]++', 'tld'],
                     ['text', '.example'],
                     ['variable', '', '[^\.]++', 'locale'],
@@ -352,10 +352,10 @@ class RouteCompilerTest extends TestCase
             [
                 'Route with host variables that has a default value',
                 ['/hello', ['locale' => 'a', 'tld' => 'b'], [], [], '{locale}.example.{tld}'],
-                '/hello', '#^/hello$#sD', ['locale', 'tld'], [], [
+                '/hello', '{^/hello$}sD', ['locale', 'tld'], [], [
                     ['text', '/hello'],
                 ],
-                '#^(?P<locale>[^\.]++)\.example\.(?P<tld>[^\.]++)$#sDi', ['locale', 'tld'], [
+                '{^(?P<locale>[^\.]++)\.example\.(?P<tld>[^\.]++)$}sDi', ['locale', 'tld'], [
                     ['variable', '.', '[^\.]++', 'tld'],
                     ['text', '.example'],
                     ['variable', '', '[^\.]++', 'locale'],
@@ -383,12 +383,12 @@ class RouteCompilerTest extends TestCase
 
     public function provideRemoveCapturingGroup()
     {
-        yield ['#^/(?P<foo>a(?:b|c)(?:d|e)f)$#sD', 'a(b|c)(d|e)f'];
-        yield ['#^/(?P<foo>a\(b\)c)$#sD', 'a\(b\)c'];
-        yield ['#^/(?P<foo>(?:b))$#sD', '(?:b)'];
-        yield ['#^/(?P<foo>(?(b)b))$#sD', '(?(b)b)'];
-        yield ['#^/(?P<foo>(*F))$#sD', '(*F)'];
-        yield ['#^/(?P<foo>(?:(?:foo)))$#sD', '((foo))'];
+        yield ['{^/(?P<foo>a(?:b|c)(?:d|e)f)$}sD', 'a(b|c)(d|e)f'];
+        yield ['{^/(?P<foo>a\(b\)c)$}sD', 'a\(b\)c'];
+        yield ['{^/(?P<foo>(?:b))$}sD', '(?:b)'];
+        yield ['{^/(?P<foo>(?(b)b))$}sD', '(?(b)b)'];
+        yield ['{^/(?P<foo>(*F))$}sD', '(*F)'];
+        yield ['{^/(?P<foo>(?:(?:foo)))$}sD', '((foo))'];
     }
 }
 
diff --git a/src/Symfony/Component/Routing/Tests/RouteTest.php b/src/Symfony/Component/Routing/Tests/RouteTest.php
index 93f397def2..36571ca027 100644
--- a/src/Symfony/Component/Routing/Tests/RouteTest.php
+++ b/src/Symfony/Component/Routing/Tests/RouteTest.php
@@ -260,7 +260,7 @@ class RouteTest extends TestCase
      */
     public function testSerializedRepresentationKeepsWorking()
     {
-        $serialized = 'C:31:"Symfony\Component\Routing\Route":936:{a:8:{s:4:"path";s:13:"/prefix/{foo}";s:4:"host";s:20:"{locale}.example.net";s:8:"defaults";a:1:{s:3:"foo";s:7:"default";}s:12:"requirements";a:1:{s:3:"foo";s:3:"\d+";}s:7:"options";a:1:{s:14:"compiler_class";s:39:"Symfony\Component\Routing\RouteCompiler";}s:7:"schemes";a:0:{}s:7:"methods";a:0:{}s:8:"compiled";C:39:"Symfony\Component\Routing\CompiledRoute":571:{a:8:{s:4:"vars";a:2:{i:0;s:6:"locale";i:1;s:3:"foo";}s:11:"path_prefix";s:7:"/prefix";s:10:"path_regex";s:31:"#^/prefix(?:/(?P<foo>\d+))?$#sD";s:11:"path_tokens";a:2:{i:0;a:4:{i:0;s:8:"variable";i:1;s:1:"/";i:2;s:3:"\d+";i:3;s:3:"foo";}i:1;a:2:{i:0;s:4:"text";i:1;s:7:"/prefix";}}s:9:"path_vars";a:1:{i:0;s:3:"foo";}s:10:"host_regex";s:40:"#^(?P<locale>[^\.]++)\.example\.net$#sDi";s:11:"host_tokens";a:2:{i:0;a:2:{i:0;s:4:"text";i:1;s:12:".example.net";}i:1;a:4:{i:0;s:8:"variable";i:1;s:0:"";i:2;s:7:"[^\.]++";i:3;s:6:"locale";}}s:9:"host_vars";a:1:{i:0;s:6:"locale";}}}}}';
+        $serialized = 'C:31:"Symfony\Component\Routing\Route":936:{a:8:{s:4:"path";s:13:"/prefix/{foo}";s:4:"host";s:20:"{locale}.example.net";s:8:"defaults";a:1:{s:3:"foo";s:7:"default";}s:12:"requirements";a:1:{s:3:"foo";s:3:"\d+";}s:7:"options";a:1:{s:14:"compiler_class";s:39:"Symfony\Component\Routing\RouteCompiler";}s:7:"schemes";a:0:{}s:7:"methods";a:0:{}s:8:"compiled";C:39:"Symfony\Component\Routing\CompiledRoute":571:{a:8:{s:4:"vars";a:2:{i:0;s:6:"locale";i:1;s:3:"foo";}s:11:"path_prefix";s:7:"/prefix";s:10:"path_regex";s:31:"{^/prefix(?:/(?P<foo>\d+))?$}sD";s:11:"path_tokens";a:2:{i:0;a:4:{i:0;s:8:"variable";i:1;s:1:"/";i:2;s:3:"\d+";i:3;s:3:"foo";}i:1;a:2:{i:0;s:4:"text";i:1;s:7:"/prefix";}}s:9:"path_vars";a:1:{i:0;s:3:"foo";}s:10:"host_regex";s:40:"{^(?P<locale>[^\.]++)\.example\.net$}sDi";s:11:"host_tokens";a:2:{i:0;a:2:{i:0;s:4:"text";i:1;s:12:".example.net";}i:1;a:4:{i:0;s:8:"variable";i:1;s:0:"";i:2;s:7:"[^\.]++";i:3;s:6:"locale";}}s:9:"host_vars";a:1:{i:0;s:6:"locale";}}}}}';
         $unserialized = unserialize($serialized);
 
         $route = new Route('/prefix/{foo}', ['foo' => 'default'], ['foo' => '\d+']);