diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index e01f3e5f3b..54bb114dec 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -168,7 +168,9 @@ def start(config_options):
     )
 
     ps.setup()
-    reactor.callWhenRunning(_base.start, ps, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ps, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-appservice", config)
 
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index 29bddc4823..721bb5b119 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -194,7 +194,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-client-reader", config)
 
diff --git a/synapse/app/event_creator.py b/synapse/app/event_creator.py
index 042cfd04af..473c8895d0 100644
--- a/synapse/app/event_creator.py
+++ b/synapse/app/event_creator.py
@@ -193,7 +193,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-event-creator", config)
 
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index 76a97f8f32..5255d9e8cc 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -175,7 +175,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-federation-reader", config)
 
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index fec49d5092..c5a2880e69 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -198,7 +198,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-federation-sender", config)
 
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index 1f1f1df78e..5b563c2778 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -247,7 +247,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-frontend-proxy", config)
 
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 0c075cb3f1..34c3f5ee99 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -447,7 +447,7 @@ def setup(config_options):
                 reactor.stop()
             sys.exit(1)
 
-    reactor.callWhenRunning(start)
+    reactor.addSystemEventTrigger("before", "startup", start)
 
     return hs
 
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index d70780e9d5..ea26f29acb 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -161,7 +161,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-media-repository", config)
 
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index 070de7d0b0..692ffa2f04 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -216,7 +216,7 @@ def start(config_options):
         _base.start(ps, config.worker_listeners)
         ps.get_pusherpool().start()
 
-    reactor.callWhenRunning(start)
+    reactor.addSystemEventTrigger("before", "startup", start)
 
     _base.start_worker_reactor("synapse-pusher", config)
 
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 315c030694..a1c3b162f7 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -451,7 +451,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-synchrotron", config)
 
diff --git a/synapse/app/user_dir.py b/synapse/app/user_dir.py
index 03ef21bd01..cb29a1afab 100644
--- a/synapse/app/user_dir.py
+++ b/synapse/app/user_dir.py
@@ -224,7 +224,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-user-dir", config)