diff --git a/CHANGELOG.md b/CHANGELOG.md
index f79f2f5..3120b20 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ Format based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 For version numbers I try to follow [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## v2.1.1
+### Fixed
+- Attempting to guess the file format of a non UTF-16 file would crash the
+  yubiosi 2.0 format guesser, not anymore.
+
 ## v2.1.0
 ### Added
 - [yubiosi] 🎉 initial yubiosi support !
diff --git a/jubeatools/formats/guess.py b/jubeatools/formats/guess.py
index dffa041..9b1e3bc 100644
--- a/jubeatools/formats/guess.py
+++ b/jubeatools/formats/guess.py
@@ -13,7 +13,7 @@ def guess_format(path: Path) -> Format:
     format is unknown"""
     if path.is_dir():
         raise ValueError("Can't guess chart format for a folder")
-    
+
     contents = path.read_bytes()
 
     return guess_file_format(contents)
@@ -238,4 +238,4 @@ def line_has_yubiosi_tag(line: str) -> bool:
 def looks_like_yubiosi_2_0(contents: bytes) -> bool:
     text = contents.decode("utf-16")
     lines = text.splitlines()
-    return lines and lines[0] == "//Yubiosi 2.0"
+    return len(lines) >= 1 and lines[0] == "//Yubiosi 2.0"
diff --git a/jubeatools/formats/tests/test_guess.py b/jubeatools/formats/tests/test_guess.py
index 139393a..b1dbcbd 100644
--- a/jubeatools/formats/tests/test_guess.py
+++ b/jubeatools/formats/tests/test_guess.py
@@ -1,13 +1,13 @@
-from pathlib import Path
-
 import hypothesis.strategies as st
-from hypothesis import given, settings
+from hypothesis import given
 
 from .. import guess
 
 
 @given(st.binary())
-def test_that_guess_format_only_raises_the_specific_value_error(contents: bytes):
+def test_that_guess_format_only_raises_the_specific_value_error(
+    contents: bytes,
+) -> None:
     try:
         guess.guess_file_format(contents)
     except ValueError as e:
@@ -15,7 +15,7 @@ def test_that_guess_format_only_raises_the_specific_value_error(contents: bytes)
             raise
 
 
-def test_that_yubiosi_2_0_detection_does_not_raise_exception_for_non_utf16_files():
+def test_that_yubiosi_2_0_detection_does_not_raise_exception_for_non_utf16_files() -> None:
     text = "blablabla"
     bytes_ = text.encode("ascii")
-    guess.looks_like_yubiosi_2_0(bytes_)
\ No newline at end of file
+    guess.looks_like_yubiosi_2_0(bytes_)