diff --git a/src/RouteMatcher/DefaultRouteMatcher.php b/src/RouteMatcher/DefaultRouteMatcher.php
index 07ffbd5..5654e30 100644
--- a/src/RouteMatcher/DefaultRouteMatcher.php
+++ b/src/RouteMatcher/DefaultRouteMatcher.php
@@ -305,7 +305,7 @@ protected function parseDefinition($def)
                 $options = preg_split('/ *\| */', trim($m['options']), 0, PREG_SPLIT_NO_EMPTY);
 
                 // remove dupes
-                array_unique($options);
+                $options = array_unique($options);
 
                 // prepare item
                 $item = [
@@ -343,7 +343,7 @@ protected function parseDefinition($def)
                 $options = preg_split('/ *\| */', trim($m['options']), 0, PREG_SPLIT_NO_EMPTY);
 
                 // remove dupes
-                array_unique($options);
+                $options = array_unique($options);
 
                 // prepare item
                 $item = [
@@ -381,7 +381,7 @@ protected function parseDefinition($def)
                 $options = preg_split('/ *\| */', trim($m['options']), 0, PREG_SPLIT_NO_EMPTY);
 
                 // remove dupes
-                array_unique($options);
+                $options = array_unique($options);
 
                 // remove prefix
                 array_walk($options, function (&$val) {
@@ -424,7 +424,7 @@ protected function parseDefinition($def)
                 $options = preg_split('/ *\| */', trim($m['options']), 0, PREG_SPLIT_NO_EMPTY);
 
                 // remove dupes
-                array_unique($options);
+                $options = array_unique($options);
 
                 // remove prefix
                 array_walk($options, function (&$val) {
diff --git a/test/RouteMatcher/DefaultRouteMatcherTest.php b/test/RouteMatcher/DefaultRouteMatcherTest.php
index 76c3287..fe48d8b 100644
--- a/test/RouteMatcher/DefaultRouteMatcherTest.php
+++ b/test/RouteMatcher/DefaultRouteMatcherTest.php
@@ -86,6 +86,15 @@ public static function routeProvider()
                 ['--baz'],
                 null
             ],
+            'mandatory-long-flag-alternative-duplicates' => [
+                '(--foo | --foo | --bar)',
+                ['--foo'],
+                [
+                    'foo' => true,
+                    'bar' => false,
+                    'baz' => null,
+                ]
+            ],
 
             // -- mandatory short flags
             'mandatory-short-flag-no-match' => [
@@ -375,6 +384,11 @@ public static function routeProvider()
                 ['foo','bar'],
                 ['foo' => null, 'altGroup' => 'bar', 'bar' => true, 'baz' => false]
             ],
+            'mandatory-literal-namedAlternative-match-1-duplicates' => [
+                'foo ( bar | bar | baz ):altGroup',
+                ['foo','bar'],
+                ['foo' => null, 'altGroup' => 'bar', 'bar' => true, 'baz' => false]
+            ],
             'mandatory-literal-namedAlternative-match-2' => [
                 'foo ( bar |   baz   ):altGroup9',
                 ['foo','baz'],