diff --git a/system/Filters/Filters.php b/system/Filters/Filters.php
index fa27dc7b518d..963638bdfb8f 100644
--- a/system/Filters/Filters.php
+++ b/system/Filters/Filters.php
@@ -376,6 +376,8 @@ private function setToolbarToLast(array $filters, bool $remove = false): array
      *
      * @param string|null $uri URI path relative to baseURL (all lowercase)
      *
+     * @TODO We don't need to accept null as $uri.
+     *
      * @return Filters
      */
     public function initialize(?string $uri = null)
@@ -385,7 +387,7 @@ public function initialize(?string $uri = null)
         }
 
         // Decode URL-encoded string
-        $uri = urldecode($uri);
+        $uri = urldecode($uri ?? '');
 
         $oldFilterOrder = config(Feature::class)->oldFilterOrder ?? false;
         if ($oldFilterOrder) {
diff --git a/tests/system/Commands/Utilities/ConfigCheckTest.php b/tests/system/Commands/Utilities/ConfigCheckTest.php
index 00066e472187..9d2c5fdfd3d3 100644
--- a/tests/system/Commands/Utilities/ConfigCheckTest.php
+++ b/tests/system/Commands/Utilities/ConfigCheckTest.php
@@ -96,6 +96,7 @@ public function testGetKintD()
                     public 'allowedHostnames' -> array (0) []
                     public 'indexPage' -> string (9) "index.php"
                     public 'uriProtocol' -> string (11) "REQUEST_URI"
+                    public 'permittedURIChars' -> string (14) "a-z 0-9~%.:_\-"
                     public 'defaultLocale' -> string (2) "en"
                     public 'negotiateLocale' -> boolean false
                     public 'supportedLocales' -> array (1) [
@@ -150,6 +151,8 @@ public function testGetVarDump()
                       string(9) "index.php"
                       public string $uriProtocol =>
                       string(11) "REQUEST_URI"
+                      public string $permittedURIChars =>
+                      string(14) "a-z 0-9~%.:_\-"
                       public string $defaultLocale =>
                       string(2) "en"
                       public bool $negotiateLocale =>
@@ -192,6 +195,8 @@ public function testGetVarDump()
                       string(9) "index.php"
                       ["uriProtocol"]=>
                       string(11) "REQUEST_URI"
+                      ["permittedURIChars"]=>
+                      string(14) "a-z 0-9~%.:_\-"
                       ["defaultLocale"]=>
                       string(2) "en"
                       ["negotiateLocale"]=>
diff --git a/tests/system/Filters/FiltersTest.php b/tests/system/Filters/FiltersTest.php
index ef8d2a9b0cac..7905cfefdae6 100644
--- a/tests/system/Filters/FiltersTest.php
+++ b/tests/system/Filters/FiltersTest.php
@@ -1097,8 +1097,8 @@ public function testMatchesURIWithUnicode(): void
                 'frak',
             ],
             'after' => [
-                'baz',
                 'frak',
+                'baz',
             ],
         ];
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());