diff --git a/distributed/tests/test_scheduler.py b/distributed/tests/test_scheduler.py
index affa58702c..7f2e7f942b 100644
--- a/distributed/tests/test_scheduler.py
+++ b/distributed/tests/test_scheduler.py
@@ -420,7 +420,7 @@ def func(scheduler):
 @gen_cluster(
     nthreads=[], config={"distributed.scheduler.blocked-handlers": ["test-handler"]}
 )
-def test_scheduler_init_pulls_blocked_handlers_from_config(s):
+async def test_scheduler_init_pulls_blocked_handlers_from_config(s):
     assert s.blocked_handlers == ["test-handler"]
 
 
diff --git a/distributed/tests/test_utils_test.py b/distributed/tests/test_utils_test.py
index db289f75d9..2ee91d8d36 100755
--- a/distributed/tests/test_utils_test.py
+++ b/distributed/tests/test_utils_test.py
@@ -106,27 +106,6 @@ def assert_config():
     await c.run_on_scheduler(assert_config)
 
 
-@gen_cluster(client=True)
-def test_gen_cluster_legacy_implicit(c, s, a, b):
-    assert isinstance(c, Client)
-    assert isinstance(s, Scheduler)
-    for w in [a, b]:
-        assert isinstance(w, Worker)
-    assert s.nthreads == {w.address: w.nthreads for w in [a, b]}
-    assert (yield c.submit(lambda: 123)) == 123
-
-
-@gen_cluster(client=True)
-@gen.coroutine
-def test_gen_cluster_legacy_explicit(c, s, a, b):
-    assert isinstance(c, Client)
-    assert isinstance(s, Scheduler)
-    for w in [a, b]:
-        assert isinstance(w, Worker)
-    assert s.nthreads == {w.address: w.nthreads for w in [a, b]}
-    assert (yield c.submit(lambda: 123)) == 123
-
-
 @pytest.mark.skip(reason="This hangs on travis")
 def test_gen_cluster_cleans_up_client(loop):
     import dask.context
diff --git a/distributed/utils_test.py b/distributed/utils_test.py
index 9770bd2cd7..8584345c41 100644
--- a/distributed/utils_test.py
+++ b/distributed/utils_test.py
@@ -919,7 +919,7 @@ async def test_foo(scheduler, worker1, worker2, pytest_fixture_a, pytest_fixture
 
     def _(func):
         if not iscoroutinefunction(func):
-            func = gen.coroutine(func)
+            raise RuntimeError("gen_cluster only works for coroutine functions.")
 
         @functools.wraps(func)
         def test_func(*outer_args, **kwargs):
@@ -964,11 +964,11 @@ async def coro():
                             )
                             args = [c] + args
                         try:
-                            future = func(*args, *outer_args, **kwargs)
-                            task = asyncio.create_task(future)
+                            coro = func(*args, *outer_args, **kwargs)
+                            task = asyncio.create_task(coro)
 
-                            future = asyncio.wait_for(asyncio.shield(task), timeout)
-                            result = await future
+                            coro2 = asyncio.wait_for(asyncio.shield(task), timeout)
+                            result = await coro2
                             if s.validate:
                                 s.validate_state()
                         except asyncio.TimeoutError:
@@ -981,7 +981,7 @@ async def coro():
                             while not task.cancelled():
                                 await asyncio.sleep(0.01)
                             raise TimeoutError(
-                                f"Test timeout.\n{buffer.getvalue()}"
+                                f"Test timeout after {timeout}s.\n{buffer.getvalue()}"
                             ) from None
                         finally:
                             if client and c.status not in ("closing", "closed"):