diff --git a/distributed/tests/test_client_executor.py b/distributed/tests/test_client_executor.py
index 49c1fc884aa..1019c2d59f8 100644
--- a/distributed/tests/test_client_executor.py
+++ b/distributed/tests/test_client_executor.py
@@ -14,9 +14,10 @@
 import pytest
 from tlz import take
 
+from distributed.event import Event
 from distributed.metrics import time
 from distributed.utils import CancelledError
-from distributed.utils_test import inc, slowadd, slowdec, slowinc, throws, varying
+from distributed.utils_test import inc, slowadd, slowinc, throws, varying
 
 
 def number_of_processing_tasks(client):
@@ -52,26 +53,38 @@ def test_as_completed(client):
 
 
 def test_wait(client):
+    def block_inc(x, ev):
+        ev.wait()
+        return x + 1
+
     with client.get_executor(pure=False) as e:
+        ev = Event()
         N = 10
-        fs = [e.submit(slowinc, i, delay=0.05) for i in range(N)]
+        fs = [e.submit(block_inc, i, ev, pure=False) for i in range(N)]
         res = wait(fs, timeout=0.01)
         assert len(res.not_done) > 0
+        ev.set()
         res = wait(fs)
         assert len(res.not_done) == 0
         assert res.done == set(fs)
+        ev.clear()
 
-        fs = [e.submit(slowinc, i, delay=0.05) for i in range(N)]
+        nthreads = sum(client.nthreads().values())
+        fs = [e.submit(block_inc, i, ev, pure=False) for i in range(nthreads - 1)]
+        fs.append(e.submit(inc, 0))
+        fs.extend([e.submit(block_inc, i, ev, pure=False) for i in range(nthreads, N)])
         res = wait(fs, return_when=FIRST_COMPLETED)
         assert len(res.not_done) > 0
         assert len(res.done) >= 1
+        ev.set()
         res = wait(fs)
         assert len(res.not_done) == 0
         assert res.done == set(fs)
+        ev.clear()
 
-        fs = [e.submit(slowinc, i, delay=0.05) for i in range(N)]
+        fs = [e.submit(inc, i) for i in range(N)]
         fs += [e.submit(throws, None)]
-        fs += [e.submit(slowdec, i, delay=0.05) for i in range(N)]
+        fs += [e.submit(block_inc, i, ev, pure=False) for i in range(N)]
         res = wait(fs, return_when=FIRST_EXCEPTION)
         assert any(f.exception() for f in res.done)
         assert res.not_done
@@ -85,6 +98,7 @@ def test_wait(client):
 
         assert len(errors) == 1
         assert "hello" in str(errors[0])
+        ev.set()
 
 
 def test_cancellation(client):