diff --git a/hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/interceptor/auth/RuleBuilder.java b/hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/interceptor/auth/RuleBuilder.java
index 47ab01ccf34..a4447bff1bd 100644
--- a/hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/interceptor/auth/RuleBuilder.java
+++ b/hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/interceptor/auth/RuleBuilder.java
@@ -451,7 +451,7 @@ public class RuleBuilder implements IAuthRuleBuilder {
 				private Collection<? extends IIdType> myInCompartmentOwners;
 				private Collection<IIdType> myAppliesToInstances;
 				private RuleImplOp myRule;
-				private List<String> myAdditionalSearchParamsForCompartmentTypes;
+				private List<String> myAdditionalSearchParamsForCompartmentTypes = new ArrayList<>();
 
 				/**
 				 * Constructor