diff --git a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtRouter.java b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtRouter.java
index 4bf04a2..98653d9 100644
--- a/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtRouter.java
+++ b/apps/kubevirt-networking/api/src/main/java/org/onosproject/kubevirtnetworking/api/DefaultKubevirtRouter.java
@@ -80,12 +80,20 @@
 
     @Override
     public Set<String> internal() {
-        return ImmutableSet.copyOf(internal);
+        if (internal == null) {
+            return ImmutableSet.of();
+        } else {
+            return ImmutableSet.copyOf(internal);
+        }
     }
 
     @Override
     public Map<String, String> external() {
-        return ImmutableMap.copyOf(external);
+        if (external == null) {
+            return ImmutableMap.of();
+        } else {
+            return ImmutableMap.copyOf(external);
+        }
     }
 
     @Override