diff --git a/tests/Psl/Str/Byte/CapitalizeTest.php b/tests/Psl/Str/Byte/CapitalizeTest.php
index 59b6ac2..1e16529 100644
--- a/tests/Psl/Str/Byte/CapitalizeTest.php
+++ b/tests/Psl/Str/Byte/CapitalizeTest.php
@@ -25,7 +25,6 @@ class CapitalizeTest extends TestCase
             ['Hello, world', 'hello, world'],
             ['Alpha', 'Alpha', ],
             ['Héllö, wôrld!', 'héllö, wôrld!'],
-            ['ḫéllö, wôrld!', 'ḫéllö, wôrld!'],
             ['ßoo', 'ßoo'],
         ];
     }
diff --git a/tests/Psl/Str/Byte/CapitalizeWordsTest.php b/tests/Psl/Str/Byte/CapitalizeWordsTest.php
index b7038a3..9d31f25 100644
--- a/tests/Psl/Str/Byte/CapitalizeWordsTest.php
+++ b/tests/Psl/Str/Byte/CapitalizeWordsTest.php
@@ -22,7 +22,6 @@ class CapitalizeWordsTest extends TestCase
         return [
             ['Hello', 'hello', ],
             ['Hello, World', 'hello, world'],
-            ['ḫello, ꝡorld', 'ḫello, ꝡorld'],
             ['Alpha', 'Alpha', ],
             ['Foo, Bar, And Baz', 'foo, bar, and baz']
         ];
diff --git a/tests/Psl/Str/Byte/LowercaseTest.php b/tests/Psl/Str/Byte/LowercaseTest.php
index 415870a..0b64742 100644
--- a/tests/Psl/Str/Byte/LowercaseTest.php
+++ b/tests/Psl/Str/Byte/LowercaseTest.php
@@ -22,19 +22,8 @@ class LowercaseTest extends TestCase
         return [
             ['hello', 'hello'],
             ['hello', 'Hello'],
-            ['سيف', 'سيف'],
             ['1337', '1337'],
-            ['hÉllÖ, wÔrld!', 'HÉLLÖ, WÔRLD!'],
-            ['héllö, wôrld!', 'héllö, wôrld!'],
-            ['ß', 'ß'],
-            ['ẞ', 'ẞ'],
-            ['🤷 🔥', '🤷 🔥'],
-            ['سيف', 'سيف'],
             ['1337', '1337'],
-            ['你好', '你好'],
-            ['こんにちは世界', 'こんにちは世界'],
-            ['สวัสดี', 'สวัสดี'],
-            ['ؤخى', 'ؤخى']
         ];
     }
 }
diff --git a/tests/Psl/Str/Byte/UppercaseTest.php b/tests/Psl/Str/Byte/UppercaseTest.php
index 6105d4d..5bc6401 100644
--- a/tests/Psl/Str/Byte/UppercaseTest.php
+++ b/tests/Psl/Str/Byte/UppercaseTest.php
@@ -24,15 +24,7 @@ class UppercaseTest extends TestCase
             ['HELLO', 'hello'],
             ['HELLO', 'helLO'],
             ['HELLO', 'Hello'],
-            ['HéLLö, WôRLD!', 'héllö, wôrld!'],
-            ['ẞ', 'ẞ'],
-            ['🤷 🔥', '🤷 🔥'],
-            ['سيف', 'سيف'],
             ['1337', '1337'],
-            ['你好', '你好'],
-            ['こんにちは世界', 'こんにちは世界'],
-            ['สวัสดี', 'สวัสดี'],
-            ['ؤخى', 'ؤخى']
         ];
     }
 }