diff --git a/src/cmd/flux-simulator b/src/cmd/flux-simulator
index 6c88df4c84cf..040328b384b8 100755
--- a/src/cmd/flux-simulator
+++ b/src/cmd/flux-simulator
@@ -108,11 +108,9 @@ class Job(object):
         logger.debug("Starting job {}".format(self.jobid))
         self.start_time = start_time
         self._start_msg = start_msg.copy()
-        flux_handle.respond(self._start_msg, payload={
-            "id": self.jobid,
-            "type": "start",
-            "data": {}
-        })
+        flux_handle.respond(
+            self._start_msg, payload={"id": self.jobid, "type": "start", "data": {}}
+        )
 
     def complete(self):
         raise NotImplementedError()
@@ -180,10 +178,7 @@ class Simulation(object):
     def start_job(self, jobid, start_msg):
         job = self.job_map[jobid]
         job.start(self.flux_handle, start_msg, self.current_time)
-        self.add_event(
-            job.complete_time,
-            lambda: self.complete_job(job)
-        )
+        self.add_event(job.complete_time, lambda: self.complete_job(job))
 
     def complete_job(self, job):
         pass
@@ -199,10 +194,9 @@ class Simulation(object):
         for event in events_at_time:
             event()
         logger.debug("Sending quiescent request for time {}".format(self.current_time))
-        self.flux_handle.rpc(
-            "job-manager.quiescent",
-            {"time":self.current_time}
-        ).then(system_quiescent_continuation, arg=self)
+        self.flux_handle.rpc("job-manager.quiescent", {"time": self.current_time}).then(
+            system_quiescent_continuation, arg=self
+        )
 
 
 def datetime_to_epoch(dt):
@@ -368,12 +362,13 @@ def job_exception_cb(flux_handle, watcher, msg, cb_args):
 def sim_exec_start_cb(flux_handle, watcher, msg, simulation):
     payload = msg.payload
     logger.debug("Received sim-exec.start request. Payload: {}".format(payload))
-    jobid = payload['id']
+    jobid = payload["id"]
     simulation.start_job(jobid, msg)
 
+
 def exec_hello(flux_handle):
     logger.debug("Registering sim-exec with job-manager")
-    flux_handle.rpc("job-manager.exec-hello", payload={"service":"sim-exec"}).get()
+    flux_handle.rpc("job-manager.exec-hello", payload={"service": "sim-exec"}).get()
 
 
 def service_add(f, name):
@@ -390,16 +385,18 @@ def setup_watchers(flux_handle, simulation):
     watchers = []
     services = set()
     for type_mask, topic, cb, args in [
-            (flux.constants.FLUX_MSGTYPE_EVENT, "job-state", job_state_cb, simulation),
-            (flux.constants.FLUX_MSGTYPE_REQUEST, "sim-exec.start", sim_exec_start_cb, simulation),
+        (flux.constants.FLUX_MSGTYPE_EVENT, "job-state", job_state_cb, simulation),
+        (
+            flux.constants.FLUX_MSGTYPE_REQUEST,
+            "sim-exec.start",
+            sim_exec_start_cb,
+            simulation,
+        ),
     ]:
         if type_mask == flux.constants.FLUX_MSGTYPE_EVENT:
             flux_handle.event_subscribe(topic)
         watcher = flux_handle.msg_watcher_create(
-            cb,
-            type_mask=type_mask,
-            topic_glob=topic,
-            args=args,
+            cb, type_mask=type_mask, topic_glob=topic, args=args
         )
         watcher.start()
         watchers.append(watcher)
@@ -452,5 +449,6 @@ def main():
     flux_handle.reactor_run(flux_handle.get_reactor(), 0)
     teardown_watchers(flux_handle, watchers, services)
 
+
 if __name__ == "__main__":
     main()