diff --git a/Source/Concurrency/YieldingProcDuplicator.cs b/Source/Concurrency/YieldingProcDuplicator.cs
index 19794052c..7aec29a55 100644
--- a/Source/Concurrency/YieldingProcDuplicator.cs
+++ b/Source/Concurrency/YieldingProcDuplicator.cs
@@ -347,11 +347,9 @@ private void ProcessParCallCmd(ParCallCmd parCall, ParCallCmd newParCall)
                         newCallCmds.Add(pair.Item2);
                     }
                 }
-                if (newCallCmds.Count > 0)
-                {
-                    newParCall.CallCmds = newCallCmds;
-                    newCmdSeq.Add(newParCall);
-                }
+                Debug.Assert(newCallCmds.Count > 0);
+                newParCall.CallCmds = newCallCmds;
+                newCmdSeq.Add(newParCall);
             }
         }