diff --git a/src/IO/Directory.php b/src/IO/Directory.php
index e1332c8e..f45518bf 100644
--- a/src/IO/Directory.php
+++ b/src/IO/Directory.php
@@ -102,7 +102,7 @@ class Directory
         foreach ($split_path as $path_part) {
             $existing_path .= $path_part . self::SEPARATOR;
 
-            if ($on_windows && substr($existing_path, 1, 2) === ':\\') {
+            if ($on_windows && substr($path_part, 1, 2) === ':\\') {
                 continue;
             }
 
diff --git a/tests/ZalgoTest.php b/tests/ZalgoTest.php
index c3eff2d6..30c9eabb 100644
--- a/tests/ZalgoTest.php
+++ b/tests/ZalgoTest.php
@@ -2,7 +2,6 @@
 namespace MisuzuTests;
 
 use PHPUnit\Framework\TestCase;
-use Misuzu\Zalgo;
 
 class ZalgoTest extends TestCase
 {
@@ -12,17 +11,17 @@ class ZalgoTest extends TestCase
     {
         $this->assertEquals(
             static::TEST_STRING,
-            Zalgo::strip(Zalgo::run(static::TEST_STRING, Zalgo::ZALGO_MODE_MINI))
+            zalgo_strip(zalgo_run(static::TEST_STRING, MSZ_ZALGO_MODE_MINI))
         );
 
         $this->assertEquals(
             static::TEST_STRING,
-            Zalgo::strip(Zalgo::run(static::TEST_STRING, Zalgo::ZALGO_MODE_NORMAL))
+            zalgo_strip(zalgo_run(static::TEST_STRING, MSZ_ZALGO_MODE_NORMAL))
         );
 
         $this->assertEquals(
             static::TEST_STRING,
-            Zalgo::strip(Zalgo::run(static::TEST_STRING, Zalgo::ZALGO_MODE_MAX))
+            zalgo_strip(zalgo_run(static::TEST_STRING, MSZ_ZALGO_MODE_MAX))
         );
     }
 }