diff --git a/artiq/frontend/artiq_run.py b/artiq/frontend/artiq_run.py
index f982dff1b..76f2cbc4b 100755
--- a/artiq/frontend/artiq_run.py
+++ b/artiq/frontend/artiq_run.py
@@ -118,7 +118,8 @@ def main():
             if args.arguments:
                 print("Run arguments are not supported in ELF mode")
                 sys.exit(1)
-            exp_inst = ELFRunner(dps)
+            exp_inst = ELFRunner(dbh)
+            rdb.build()
             exp_inst.run(args.file)
         else:
             module = file_import(args.file)
@@ -159,6 +160,7 @@ def main():
                            scheduler=DummyScheduler(),
                            run_params=run_params,
                            **run_params["arguments"])
+            rdb.build()
             exp_inst.run()
             exp_inst.analyze()
 
diff --git a/artiq/language/db.py b/artiq/language/db.py
index 117a23835..16f0fb4a5 100644
--- a/artiq/language/db.py
+++ b/artiq/language/db.py
@@ -83,7 +83,7 @@ class AutoDB:
                     object.__setattr__(self, k, dev)
         self.build()
         if self.dbh is not None:
-            self.dbh.init_results(self.realtime_results)
+            self.dbh.add_rt_results(self.realtime_results)
 
     def __getattr__(self, name):
         ak = getattr(self.DBKeys, name)
diff --git a/artiq/master/worker_db.py b/artiq/master/worker_db.py
index 98e40e62f..10037d457 100644
--- a/artiq/master/worker_db.py
+++ b/artiq/master/worker_db.py
@@ -10,13 +10,18 @@ class ResultDB:
     def __init__(self, init_rt_results, update_rt_results):
         self.init_rt_results = init_rt_results
         self.update_rt_results = update_rt_results
+        self.rtr_description = dict()
 
-    def init(self, rtr_description):
-        assert not hasattr(self, "realtime_data")
-        assert not hasattr(self, "data")
+    def add_rt_results(self, rtr_description):
+        intr = set(self.rtr_description.keys()).intersection(
+            set(rtr_description.keys()))
+        if intr:
+            raise ValueError("Duplicate realtime results: " + ", ".join(intr))
+        self.rtr_description.update(rtr_description)
 
+    def build(self):
         realtime_results_set = set()
-        for rtr in rtr_description.keys():
+        for rtr in self.rtr_description.keys():
             if isinstance(rtr, tuple):
                 for e in rtr:
                     realtime_results_set.add(e)
@@ -26,7 +31,7 @@ class ResultDB:
         self.realtime_data = Notifier({x: [] for x in realtime_results_set})
         self.data = Notifier(dict())
 
-        self.init_rt_results(rtr_description)
+        self.init_rt_results(self.rtr_description)
         self.realtime_data.publish = lambda notifier, data: \
             self.update_rt_results(data)
 
@@ -83,7 +88,7 @@ class DBHub:
 
         self.get_parameter = pdb.request
         self.set_parameter = pdb.set
-        self.init_results = rdb.init
+        self.add_rt_results = rdb.add_rt_results
         self.get_result = rdb.request
         self.set_result = rdb.set
 
diff --git a/artiq/master/worker_impl.py b/artiq/master/worker_impl.py
index f428093a4..aa788a2f1 100644
--- a/artiq/master/worker_impl.py
+++ b/artiq/master/worker_impl.py
@@ -112,6 +112,7 @@ def main():
                                scheduler=Scheduler,
                                run_params=run_params,
                                **run_params["arguments"])
+                rdb.build()
                 put_object({"action": "completed"})
             elif action == "run":
                 exp_inst.run()