diff --git a/tests/unit/wiring/test_introspection_py36.py b/tests/unit/wiring/test_introspection_py36.py
index c7149602..66b36a80 100644
--- a/tests/unit/wiring/test_introspection_py36.py
+++ b/tests/unit/wiring/test_introspection_py36.py
@@ -6,6 +6,13 @@ import inspect
 from dependency_injector.wiring import inject
 
 
+def test_isfunction():
+    @inject
+    def foo(): ...
+
+    assert inspect.isfunction(foo)
+
+
 def test_asyncio_iscoroutinefunction():
     @inject
     async def foo():