diff --git a/src/main/java/simpaths/model/PartnershipAlignment.java b/src/main/java/simpaths/model/PartnershipAlignment.java
index f06a62a91..614adf8e3 100644
--- a/src/main/java/simpaths/model/PartnershipAlignment.java
+++ b/src/main/java/simpaths/model/PartnershipAlignment.java
@@ -51,7 +51,7 @@ public PartnershipAlignment(Set<Person> persons) {
     public double evaluate(double[] args) {
 
         model.clearPersonsToMatch();
-        persons.parallelStream()
+        persons.stream()
                 .filter(person -> person.getDemAge() >= Parameters.MIN_AGE_COHABITATION)
                 .forEach(person -> person.cohabitation(args[0]));