diff --git a/contribs/drt-extensions/src/main/java/org/matsim/contrib/drt/extension/companions/DrtCompanionRideGenerator.java b/contribs/drt-extensions/src/main/java/org/matsim/contrib/drt/extension/companions/DrtCompanionRideGenerator.java
index 5429ca3feed..66f552ee730 100644
--- a/contribs/drt-extensions/src/main/java/org/matsim/contrib/drt/extension/companions/DrtCompanionRideGenerator.java
+++ b/contribs/drt-extensions/src/main/java/org/matsim/contrib/drt/extension/companions/DrtCompanionRideGenerator.java
@@ -87,6 +87,7 @@ private void installSampler(DrtWithExtensionsConfigGroup drtWithExtensionsConfig
 	}
 
 	void addCompanionAgents() {
+		int identifier = 0;
 		HashMap<String, Integer> drtCompanionAgents = new HashMap<>();
 		Collection<Person> companions = new ArrayList<>();
 		for (Person person : this.scenario.getPopulation().getPersons().values()) {
@@ -104,7 +105,8 @@ void addCompanionAgents() {
 						int groupPart = i;
 
 						companions.add(createCompanionAgent(mainMode, person, trip, trip.getOriginActivity(),
-								trip.getDestinationActivity(), groupPart, groupSize));
+								trip.getDestinationActivity(), groupPart, groupSize, identifier));
+						identifier++;
 					}
 				}
 			}
@@ -120,9 +122,9 @@ void addCompanionAgents() {
 	}
 
 	private Person createCompanionAgent(String drtMode, Person originalPerson, TripStructureUtils.Trip trip,
-										Activity fromActivity, Activity toActivity, int groupPart, int groupSize) {
+										Activity fromActivity, Activity toActivity, int groupPart, int groupSize, int identifier) {
 		String prefix = getCompanionPrefix(drtMode);
-		String companionId = prefix + "_" + originalPerson.getId().toString() + "_" + groupPart;
+		String companionId = prefix + "_" + originalPerson.getId().toString() + "_" + identifier;
 		Person person = PopulationUtils.getFactory().createPerson(Id.createPersonId(companionId));
 		DrtCompanionUtils.setDRTCompanionType(person, DRT_COMPANION_TYPE);