diff --git a/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php b/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php
index b77c53085495..95e0d8d3a9e4 100644
--- a/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php
+++ b/src/Symfony/Component/Routing/Matcher/Dumper/PhpMatcherTrait.php
@@ -132,7 +132,7 @@ private function doMatch(string $pathinfo, array &$allow = [], array &$allowSche
 
                     $hasTrailingVar = $trimmedPathinfo !== $pathinfo && $hasTrailingVar;
 
-                    if ($hasTrailingVar && ($hasTrailingSlash || '/' !== substr($matches[\count($vars)], -1)) && preg_match($regex, $this->matchHost ? $host.'.'.$trimmedPathinfo : $trimmedPathinfo, $n) && $m === (int) $n['MARK']) {
+                    if ($hasTrailingVar && ($hasTrailingSlash || !($n = $matches[\count($vars)] ?? '') || '/' !== substr($n, -1)) && preg_match($regex, $this->matchHost ? $host.'.'.$trimmedPathinfo : $trimmedPathinfo, $n) && $m === (int) $n['MARK']) {
                         if ($hasTrailingSlash) {
                             $matches = $n;
                         } else {
diff --git a/src/Symfony/Component/Routing/Matcher/UrlMatcher.php b/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
index 5b6c0440da9c..dda9edb7e22f 100644
--- a/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
+++ b/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
@@ -158,7 +158,7 @@ protected function matchCollection($pathinfo, RouteCollection $routes)
 
             $hasTrailingVar = $trimmedPathinfo !== $pathinfo && preg_match('#\{\w+\}/?$#', $route->getPath());
 
-            if ($hasTrailingVar && ($hasTrailingSlash || '/' !== substr($matches[(\count($matches) - 1) >> 1], -1)) && preg_match($regex, $trimmedPathinfo, $m)) {
+            if ($hasTrailingVar && ($hasTrailingSlash || !($m = $matches[\count($compiledRoute->getPathVariables())] ?? '') || '/' !== substr($m, -1)) && preg_match($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 42acb0485758..5e8114ea28db 100644
--- a/src/Symfony/Component/Routing/Tests/Matcher/RedirectableUrlMatcherTest.php
+++ b/src/Symfony/Component/Routing/Tests/Matcher/RedirectableUrlMatcherTest.php
@@ -198,6 +198,17 @@ public function testNonGreedyTrailingRequirement()
         $this->assertEquals(['_route' => 'a', 'a' => '123'], $matcher->match('/123/'));
     }
 
+    public function testTrailingRequirementWithDefault()
+    {
+        $coll = new RouteCollection();
+        $coll->add('a', new Route('/foo/{a}', ['a' => 'bar'], ['a' => '.+']));
+
+        $matcher = $this->getUrlMatcher($coll);
+        $matcher->expects($this->once())->method('redirect')->with('/foo')->willReturn([]);
+
+        $this->assertEquals(['_route' => 'a', 'a' => 'bar'], $matcher->match('/foo/'));
+    }
+
     protected function getUrlMatcher(RouteCollection $routes, RequestContext $context = null)
     {
         return $this->getMockForAbstractClass('Symfony\Component\Routing\Matcher\RedirectableUrlMatcher', [$routes, $context ?: new RequestContext()]);