diff --git a/tests/test_utils_opmsg.py b/tests/test_utils_opmsg.py
index 3b7093030..aa2b6f598 100644
--- a/tests/test_utils_opmsg.py
+++ b/tests/test_utils_opmsg.py
@@ -54,6 +54,7 @@ def ioc():
 
             # Loop WITHOUT serving values again (so client puts persist)
             while True:
+                mor.serve() 
                 time.sleep(0.02)
 
     def run_status_prefix(beamline: str):
@@ -68,6 +69,7 @@ def ioc():
 
             # Then do nothing; client updates must persist
             while True:
+                mor.serve() 
                 time.sleep(0.02)
 
     threads = []