diff --git a/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/engine/SimulationEngine.java b/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/engine/SimulationEngine.java
index 916df89c95..33fb8f5bef 100644
--- a/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/engine/SimulationEngine.java
+++ b/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/engine/SimulationEngine.java
@@ -843,7 +843,7 @@ public SimulationActivityExtract computeActivitySimulationResults(
                 .stream()
                 .map(spanToActivityInstanceId::get)
                 .toList(),
-            (activityParents.containsKey(span)) ? Optional.empty() : Optional.of(directiveId)
+            (activityParents.containsKey(span)) ? Optional.empty() : Optional.ofNullable(directiveId)
         ));
       }
     });