diff --git a/borb/io/read/tokenize/low_level_tokenizer.py b/borb/io/read/tokenize/low_level_tokenizer.py
index d085ab85..a64eaae1 100644
--- a/borb/io/read/tokenize/low_level_tokenizer.py
+++ b/borb/io/read/tokenize/low_level_tokenizer.py
@@ -236,7 +236,7 @@ def next_token(self) -> typing.Optional[Token]:
             while True:
                 ch = self._next_byte()
                 if len(ch) == 0:
-                    break
+                    return None
                 # escape char
                 if ch == b"\\":
                     ch = self._next_byte()