diff --git a/utils/src/com/cloud/utils/net/NetUtils.java b/utils/src/com/cloud/utils/net/NetUtils.java
index 905e518e956..becca37d12f 100755
--- a/utils/src/com/cloud/utils/net/NetUtils.java
+++ b/utils/src/com/cloud/utils/net/NetUtils.java
@@ -1398,6 +1398,12 @@ public class NetUtils {
         {
             return true;
         }
+        if ((one == null || other == null)
+                &&
+                !(one == null && other == null))
+        {
+            return false;
+        }
         // check 'untagged'
         if (VLAN_UNTAGGED.equalsIgnoreCase(one) && VLAN_UNTAGGED.equalsIgnoreCase(other))
         {
diff --git a/utils/test/com/cloud/utils/net/NetUtilsTest.java b/utils/test/com/cloud/utils/net/NetUtilsTest.java
index 6d145938280..600b69ee5b2 100644
--- a/utils/test/com/cloud/utils/net/NetUtilsTest.java
+++ b/utils/test/com/cloud/utils/net/NetUtilsTest.java
@@ -182,5 +182,6 @@ public class NetUtilsTest extends TestCase {
         assertTrue(NetUtils.isSameIsolationId("UnTagged", "vlan://uNtAGGED"));
         assertFalse(NetUtils.isSameIsolationId("2", "vlan://uNtAGGED"));
         assertFalse(NetUtils.isSameIsolationId("2", "vlan://3"));
+        assertFalse(NetUtils.isSameIsolationId("bla", null));
     }
 }