diff --git a/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php b/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php
index 95e0d8d3a9..b4b4256385 100644
--- a/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php
+++ b/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php
@@ -132,7 +132,7 @@ trait PhpMatcherTrait
 
                     $hasTrailingVar = $trimmedPathinfo !== $pathinfo && $hasTrailingVar;
 
-                    if ($hasTrailingVar && ($hasTrailingSlash || !($n = $matches[\count($vars)] ?? '') || '/' !== substr($n, -1)) && preg_match($regex, $this->matchHost ? $host.'.'.$trimmedPathinfo : $trimmedPathinfo, $n) && $m === (int) $n['MARK']) {
+                    if ($hasTrailingVar && ($hasTrailingSlash || (null === $n = $matches[\count($vars)] ?? null) || '/' !== ($n[-1] ?? '/')) && preg_match($regex, $this->matchHost ? $host.'.'.$trimmedPathinfo : $trimmedPathinfo, $n) && $m === (int) $n['MARK']) {
                         if ($hasTrailingSlash) {
                             $matches = $n;
                         } else {
diff --git a/src/Symfony/Component/Routing/Matcher/UrlMatcher.php b/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
index dda9edb7e2..536ed732ad 100644
--- a/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
+++ b/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
@@ -158,7 +158,7 @@ class UrlMatcher implements UrlMatcherInterface, RequestMatcherInterface
 
             $hasTrailingVar = $trimmedPathinfo !== $pathinfo && preg_match('#\{\w+\}/?$#', $route->getPath());
 
-            if ($hasTrailingVar && ($hasTrailingSlash || !($m = $matches[\count($compiledRoute->getPathVariables())] ?? '') || '/' !== substr($m, -1)) && preg_match($regex, $trimmedPathinfo, $m)) {
+            if ($hasTrailingVar && ($hasTrailingSlash || (null === $m = $matches[\count($compiledRoute->getPathVariables())] ?? null) || '/' !== ($m[-1] ?? '/')) && preg_match($regex, $trimmedPathinfo, $m)) {
                 if ($hasTrailingSlash) {
                     $matches = $m;
                 } else {
diff --git a/src/Symfony/Component/Routing/Tests/Matcher/RedirectableUrlMatcherTest.php b/src/Symfony/Component/Routing/Tests/Matcher/RedirectableUrlMatcherTest.php
index 5e8114ea28..f5ac21db90 100644
--- a/src/Symfony/Component/Routing/Tests/Matcher/RedirectableUrlMatcherTest.php
+++ b/src/Symfony/Component/Routing/Tests/Matcher/RedirectableUrlMatcherTest.php
@@ -198,15 +198,15 @@ class RedirectableUrlMatcherTest extends UrlMatcherTest
         $this->assertEquals(['_route' => 'a', 'a' => '123'], $matcher->match('/123/'));
     }
 
-    public function testTrailingRequirementWithDefault()
+    public function testTrailingRequirementWithDefault_A()
     {
         $coll = new RouteCollection();
-        $coll->add('a', new Route('/foo/{a}', ['a' => 'bar'], ['a' => '.+']));
+        $coll->add('a', new Route('/fr-fr/{a}', ['a' => 'aaa'], ['a' => '.+']));
 
         $matcher = $this->getUrlMatcher($coll);
-        $matcher->expects($this->once())->method('redirect')->with('/foo')->willReturn([]);
+        $matcher->expects($this->once())->method('redirect')->with('/fr-fr')->willReturn([]);
 
-        $this->assertEquals(['_route' => 'a', 'a' => 'bar'], $matcher->match('/foo/'));
+        $this->assertEquals(['_route' => 'a', 'a' => 'aaa'], $matcher->match('/fr-fr/'));
     }
 
     protected function getUrlMatcher(RouteCollection $routes, RequestContext $context = null)
diff --git a/src/Symfony/Component/Routing/Tests/Matcher/UrlMatcherTest.php b/src/Symfony/Component/Routing/Tests/Matcher/UrlMatcherTest.php
index 596c1476f7..ac3816f893 100644
--- a/src/Symfony/Component/Routing/Tests/Matcher/UrlMatcherTest.php
+++ b/src/Symfony/Component/Routing/Tests/Matcher/UrlMatcherTest.php
@@ -757,6 +757,41 @@ class UrlMatcherTest extends TestCase
         $this->assertEquals(['_route' => 'a', 'a' => 'foo/'], $matcher->match('/foo/'));
     }
 
+    public function testTrailingRequirementWithDefault()
+    {
+        $coll = new RouteCollection();
+        $coll->add('a', new Route('/fr-fr/{a}', ['a' => 'aaa'], ['a' => '.+']));
+        $coll->add('b', new Route('/en-en/{b}', ['b' => 'bbb'], ['b' => '.*']));
+
+        $matcher = $this->getUrlMatcher($coll);
+
+        $this->assertEquals(['_route' => 'a', 'a' => 'aaa'], $matcher->match('/fr-fr'));
+        $this->assertEquals(['_route' => 'a', 'a' => 'AAA'], $matcher->match('/fr-fr/AAA'));
+        $this->assertEquals(['_route' => 'b', 'b' => 'bbb'], $matcher->match('/en-en'));
+        $this->assertEquals(['_route' => 'b', 'b' => 'BBB'], $matcher->match('/en-en/BBB'));
+    }
+
+    public function testTrailingRequirementWithDefault_A()
+    {
+        $coll = new RouteCollection();
+        $coll->add('a', new Route('/fr-fr/{a}', ['a' => 'aaa'], ['a' => '.+']));
+
+        $matcher = $this->getUrlMatcher($coll);
+
+        $this->expectException(ResourceNotFoundException::class);
+        $matcher->match('/fr-fr/');
+    }
+
+    public function testTrailingRequirementWithDefault_B()
+    {
+        $coll = new RouteCollection();
+        $coll->add('b', new Route('/en-en/{b}', ['b' => 'bbb'], ['b' => '.*']));
+
+        $matcher = $this->getUrlMatcher($coll);
+
+        $this->assertEquals(['_route' => 'b', 'b' => ''], $matcher->match('/en-en/'));
+    }
+
     protected function getUrlMatcher(RouteCollection $routes, RequestContext $context = null)
     {
         return new UrlMatcher($routes, $context ?: new RequestContext());