diff --git a/tests/test_utils.py b/tests/test_utils.py
new file mode 100644
index 0000000..b8522d5
--- /dev/null
+++ b/tests/test_utils.py
@@ -0,0 +1,53 @@
+import pytest
+from typing import Optional
+
+from whisper.utils import optional_float, optional_int, str2bool
+
+
+@pytest.mark.parametrize(("provided", "expected"), [
+    ("TRUE", True),
+    ("True", True),
+    ("true", True),
+    ("YES", True),
+    ("Yes", True),
+    ("yes", True),
+    ("Y", True),
+    ("y", True),
+    ("1", True),
+
+    ("FALSE", False),
+    ("False", False),
+    ("false", False),
+    ("NO", False),
+    ("No", False),
+    ("no", False),
+    ("N", False),
+    ("n", False),
+    ("0", False),
+])
+def test_str2bool(provided: str, expected: bool) -> None:
+    assert str2bool(provided) is expected
+
+
+def test_str2bool_faulty_argument() -> None:
+    with pytest.raises(ValueError, match="Expected one of"):
+        str2bool("boom")
+
+
+@pytest.mark.parametrize(("provided", "expected"), [
+    ("1", 1),
+    ("None", None),
+    ("none", None),
+])
+def test_optional_int(provided: str, expected: Optional[int]) -> None:
+    assert optional_int(provided) == expected
+
+
+@pytest.mark.parametrize(("provided", "expected"), [
+    ("1.23", 1.23),
+    ("1", 1),
+    ("None", None),
+    ("none", None),
+])
+def test_optional_float(provided: str, expected: Optional[float]) -> None:
+    assert optional_float(provided) == expected
diff --git a/whisper/utils.py b/whisper/utils.py
index 9b9b138..264f18b 100644
--- a/whisper/utils.py
+++ b/whisper/utils.py
@@ -26,20 +26,21 @@ def exact_div(x, y):
     return x // y
 
 
-def str2bool(string):
-    str2val = {"True": True, "False": False}
-    if string in str2val:
-        return str2val[string]
-    else:
-        raise ValueError(f"Expected one of {set(str2val.keys())}, got {string}")
+def str2bool(string: str) -> bool:
+    if string.lower() in {'true', 'yes', 'y', '1'}:
+        return True
+    if string.lower() in {'false', 'no', 'n', '0'}:
+        return False
+
+    raise ValueError(f"Expected one of true/yes/1 or false/no/0, but got {string}")
 
 
 def optional_int(string):
-    return None if string == "None" else int(string)
+    return None if string.lower() == "none" else int(string)
 
 
 def optional_float(string):
-    return None if string == "None" else float(string)
+    return None if string.lower() == "none" else float(string)
 
 
 def compression_ratio(text) -> float: