diff --git a/tests/mask_store/test_byte_tokenizer.py b/tests/mask_store/test_byte_tokenizer.py
index e5fe11d3..b456e9fa 100644
--- a/tests/mask_store/test_byte_tokenizer.py
+++ b/tests/mask_store/test_byte_tokenizer.py
@@ -65,13 +65,13 @@ def test_raw_tokenizer(self):
         """Test ByteTokenizer with a RAW (tiktoken-style) tokenizer."""
         # Create mock vocabulary for a raw tokenizer
         vocab = {
-            "hello": 1,
-            "world": 2,
-            "!": 3,
-            "你": 4,
-            "好": 5,
-            "吗": 6,
-            "？": 7
+            b"hello": 1,
+            b"world": 2,
+            b"!": 3,
+            b"\xE4\xBD\xA0": 4, # 你
+            b"\xE5\xA5\xBD": 5, # 好
+            b"\xE5\x90": 6, # first two bytes of 吗
+            b"\x97": 7, # last byte of 吗
         }
         
         mock_tokenizer = self.create_mock_tokenizer(vocab, VocabType.RAW)
@@ -84,10 +84,10 @@ def test_raw_tokenizer(self):
         mock_tokenizer.encode.return_value = expected_ids
         
         # Test decoding
-        token_ids = [4, 5, 6, 7]  # 你, 好, 吗, ？  
+        token_ids = [4, 5, 6]  # 你, 好, 吗 (first two bytes).
         mock_tokenizer.decode.return_value = "你好吗？"
         result = byte_tokenizer.decode(token_ids)
-        self.assertEqual(result.decode('utf-8'), "你好吗？")
+        self.assertEqual(result, b"\xE4\xBD\xA0\xE5\xA5\xBD\xE5\x90")
     
     def test_byte_fallback_tokenizer(self):
         """Test ByteTokenizer with a BYTE_FALLBACK (Llama-2-style) tokenizer."""
@@ -151,11 +151,11 @@ def test_byte_level_tokenizer(self):
     def test_batched_decoding(self):
         """Test batched decoding capabilities."""
         vocab = {
-            "hello": 1,
-            "world": 2,
-            "!": 3,
-            "<s>": 4,  # special token
-            "</s>": 5,  # special token
+            b"hello": 1,
+            b"world": 2,
+            b"!": 3,
+            b"<s>": 4,  # special token
+            b"</s>": 5,  # special token
         }
         
         mock_tokenizer = self.create_mock_tokenizer(vocab, VocabType.RAW)
@@ -196,10 +196,10 @@ def test_auto_detection(self):
     def test_decoding_performance(self):
         """Test basic decoding performance."""
         # Create a larger vocabulary for more realistic testing
-        vocab = {f"token{i}": i for i in range(1000)}
+        vocab = {bytes(f"token{i}".encode('utf-8')): i for i in range(1000)}
         # Add some special tokens
-        vocab["<s>"] = 1000
-        vocab["</s>"] = 1001
+        vocab[b"<s>"] = 1000
+        vocab[b"</s>"] = 1001
         
         mock_tokenizer = self.create_mock_tokenizer(vocab, VocabType.RAW)
         mock_tokenizer.all_special_ids = [1000, 1001]
@@ -313,10 +313,10 @@ def test_roundtrip_encoding_decoding(self):
         """Test encoding and decoding round-trip."""
         # Create a simple vocabulary for testing
         raw_vocab = {
-            "hello": 1,
-            " ": 2,
-            "world": 3,
-            "!": 4,
+            b"hello": 1,
+            b" ": 2,
+            b"world": 3,
+            b"!": 4,
         }
         
         mock_tokenizer = self.create_mock_tokenizer(raw_vocab, VocabType.RAW)