diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index c95e49c3fe..68f5dd8f30 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -2459,10 +2459,9 @@ opentracing:
 #  typing: worker1
 
 # The worker that is used to run background tasks (e.g. cleaning up expired
-# data). This should be one of the workers from `instance_map`. If not
-# provided this defaults to the main process.
+# data). If not provided this defaults to the main process.
 #
-#run_background_tasks: worker1
+#run_background_tasks_on: worker1
 
 
 # Configuration for Redis when using workers. This *must* be enabled when
diff --git a/synapse/config/workers.py b/synapse/config/workers.py
index 3034eef456..5014615a08 100644
--- a/synapse/config/workers.py
+++ b/synapse/config/workers.py
@@ -182,10 +182,9 @@ class WorkerConfig(Config):
         #  typing: worker1
 
         # The worker that is used to run background tasks (e.g. cleaning up expired
-        # data). This should be one of the workers from `instance_map`. If not
-        # provided this defaults to the main process.
+        # data). If not provided this defaults to the main process.
         #
-        #run_background_tasks: worker1
+        #run_background_tasks_on: worker1
         """
 
     def read_arguments(self, args):