diff --git a/payu/experiment.py b/payu/experiment.py
index 591d26b8..6b631a8e 100644
--- a/payu/experiment.py
+++ b/payu/experiment.py
@@ -561,7 +561,7 @@ def run(self, *user_flags):
 
             for prof in self.profilers:
                 if prof.runscript:
-                    model_prog = model_prog.append(prof.runscript)
+                    model_prog.append(prof.runscript)
 
             model_prog.append(model.exec_prefix)