diff --git a/enum_tools/demo.py b/enum_tools/demo.py
index fd35d0a..69d956e 100644
--- a/enum_tools/demo.py
+++ b/enum_tools/demo.py
@@ -71,7 +71,7 @@ class StatusFlags(IntFlag):
 	Stopped = 2  # doc: The system has stopped.
 	Error = 4  # doc: An error has occurred.
 
-	def has_errored(self) -> bool:
+	def has_errored(self) -> bool:  # pragma: no cover
 		"""
 		Returns whether the operation has errored.
 		"""
diff --git a/enum_tools/utils.py b/enum_tools/utils.py
index e31f3b5..da71065 100644
--- a/enum_tools/utils.py
+++ b/enum_tools/utils.py
@@ -87,9 +87,16 @@ def get_base_object(enum: Type[HasMRO]) -> Type:
 	If the members are of indeterminate type then the :class:`object` class is returned.
 
 	:param enum:
+
+	:rtype:
+
+	:raises TypeError: If ``enum`` is not an Enum.
 	"""
 
-	mro = inspect.getmro(enum)
+	try:
+		mro = inspect.getmro(enum)
+	except AttributeError:
+		raise TypeError("not an Enum")
 
 	if Flag in mro:
 		mro = mro[:mro.index(Flag)]
diff --git a/tests/test_utils.py b/tests/test_utils.py
new file mode 100644
index 0000000..c701749
--- /dev/null
+++ b/tests/test_utils.py
@@ -0,0 +1,83 @@
+# stdlib
+import enum
+import http
+
+# 3rd party
+import pytest
+
+# this package
+from enum_tools import StrEnum
+from enum_tools.utils import get_base_object, is_enum, is_enum_member, is_flag
+
+
+@pytest.mark.parametrize(
+		"obj, result",
+		[
+				(enum.Enum, True),
+				(http.HTTPStatus, True),
+				(http.HTTPStatus.NOT_ACCEPTABLE, False),
+				(123, False),
+				("abc", False),
+				]
+		)
+def test_is_enum(obj, result):
+	assert is_enum(obj) == result
+
+
+@pytest.mark.parametrize(
+		"obj, result",
+		[
+				(enum.Enum, False),
+				(http.HTTPStatus, False),
+				(http.HTTPStatus.NOT_ACCEPTABLE, True),
+				(123, False),
+				("abc", False),
+				]
+		)
+def test_is_enum_member(obj, result):
+	assert is_enum_member(obj) == result
+
+
+class Colours(enum.Flag):
+	RED = 1
+	BLUE = 2
+
+
+PURPLE = Colours.RED | Colours.BLUE
+
+
+@pytest.mark.parametrize(
+		"obj, result",
+		[
+				(enum.Enum, False),
+				(http.HTTPStatus, False),
+				(http.HTTPStatus.NOT_ACCEPTABLE, False),
+				(123, False),
+				("abc", False),
+				(Colours, True),
+				(Colours.RED, False),
+				(PURPLE, False),
+				]
+		)
+def test_is_flag(obj, result):
+	assert is_flag(obj) == result
+
+
+def test_get_base_object():
+	# TODO: report issue to mypy
+	assert get_base_object(enum.Enum) is object  # type: ignore[arg-type]
+	assert get_base_object(Colours) is object  # type: ignore[arg-type]
+	assert get_base_object(enum.IntFlag) is int  # type: ignore[arg-type]
+	assert get_base_object(StrEnum) is str  # type: ignore[arg-type]
+
+	with pytest.raises(TypeError, match="not an Enum"):
+		get_base_object("abc")  # type: ignore[arg-type]
+
+	with pytest.raises(TypeError, match="not an Enum"):
+		get_base_object(123)  # type: ignore[arg-type]
+
+	with pytest.raises(TypeError, match="not an Enum"):
+		get_base_object(str)  # type: ignore[arg-type]
+
+	with pytest.raises(TypeError, match="not an Enum"):
+		get_base_object(int)  # type: ignore[arg-type]