diff --git a/modules/system/classes/PluginManager.php b/modules/system/classes/PluginManager.php
index 35300f6bf..a92ea6490 100644
--- a/modules/system/classes/PluginManager.php
+++ b/modules/system/classes/PluginManager.php
@@ -363,7 +363,9 @@ class PluginManager
     {
         $classId = $this->getIdentifier($namespace);
 
-        return isset($this->plugins[$classId]);
+        $normalized = $this->normalizeIdentifier($classId);
+
+        return isset($this->plugins[$normalized]);
     }
 
     /**
@@ -707,13 +709,11 @@ class PluginManager
 
         $loopCount = 0;
         while (count($checklist)) {
-
             if (++$loopCount > 999) {
                 throw new ApplicationException('Too much recursion');
             }
 
             foreach ($checklist as $code => $plugin) {
-
                 /*
                  * Get dependencies and remove any aliens
                  */
@@ -745,9 +745,7 @@ class PluginManager
                 array_push($result, $code);
                 unset($checklist[$code]);
             }
-
         }
-
         return $result;
     }
 
diff --git a/tests/unit/system/classes/PluginManagerTest.php b/tests/unit/system/classes/PluginManagerTest.php
index 445d709ea..9130b926c 100644
--- a/tests/unit/system/classes/PluginManagerTest.php
+++ b/tests/unit/system/classes/PluginManagerTest.php
@@ -117,10 +117,10 @@ class PluginManagerTest extends TestCase
          * Test case for https://github.com/octobercms/october/pull/4337
          */
         $result = $this->manager->hasPlugin('dependencyTest\Wrongcase');
-        $this->assertFalse($result);
+        $this->assertTrue($result);
 
         $result = $this->manager->hasPlugin('dependencyTest.Wrongcase');
-        $this->assertFalse($result);
+        $this->assertTrue($result);
     }
 
     public function testGetPluginNamespaces()