diff --git a/src/Routing/Route/Route.php b/src/Routing/Route/Route.php
index f2212ca97b3..0a2f9764bbe 100644
--- a/src/Routing/Route/Route.php
+++ b/src/Routing/Route/Route.php
@@ -322,7 +322,7 @@ protected function _writeRoute()
         $names = $routeParams = [];
         $parsed = preg_quote($this->template, '#');
 
-        if (strpos($route, '{') !== false) {
+        if (strpos($route, '{') !== false && strpos($route, '}') !== false) {
             preg_match_all('/\{([a-z0-9-_]+)\}/i', $route, $namedElements);
             $this->braceKeys = true;
         } else {
diff --git a/tests/TestCase/Routing/Route/RouteTest.php b/tests/TestCase/Routing/Route/RouteTest.php
index 2263a5dbf0d..e428da74fdb 100644
--- a/tests/TestCase/Routing/Route/RouteTest.php
+++ b/tests/TestCase/Routing/Route/RouteTest.php
@@ -190,6 +190,19 @@ public function testRouteCompileBraces()
      */
     public function testRouteCompileMixedPlaceholders()
     {
+        $route = new Route(
+            '/images/{open/:id',
+            ['controller' => 'Images', 'action' => 'open']
+        );
+        $pattern = $route->compile();
+        $this->assertRegExp($pattern, '/images/{open/9', 'Need both {} to enable brace mode');
+        $result = $route->match([
+            'controller' => 'Images',
+            'action' => 'open',
+            'id' => 123,
+        ]);
+        $this->assertEquals('/images/{open/123', $result);
+
         $route = new Route(
             '/fighters/{id}/move/{x}/:y',
             ['controller' => 'Fighters', 'action' => 'move'],