diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index 1dac5b7..83727bc 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -122,6 +122,8 @@
     // TODO: have this configurable
     private static final int DHCP_LEASE_TIME_SECS = 3600;
 
+    private static final MacAddress NULL_MAC_ADDRESS = MacAddress.fromString("00:00:00:00:00:00");
+
     private static final String TAG = "IpServer";
     private static final boolean DBG = false;
     private static final boolean VDBG = false;
@@ -902,9 +904,12 @@
             return;
         }
 
+        // When deleting rules, we still need to pass a non-null MAC, even though it's ignored.
+        // Do this here instead of in the Ipv6ForwardingRule constructor to ensure that we never
+        // add rules with a null MAC, only delete them.
+        MacAddress dstMac = e.isValid() ? e.macAddr : NULL_MAC_ADDRESS;
         Ipv6ForwardingRule rule = new Ipv6ForwardingRule(upstreamIfindex,
-                mInterfaceParams.index, (Inet6Address) e.ip, mInterfaceParams.macAddr,
-                e.macAddr);
+                mInterfaceParams.index, (Inet6Address) e.ip, mInterfaceParams.macAddr, dstMac);
         if (e.isValid()) {
             addIpv6ForwardingRule(rule);
         } else {
diff --git a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
index fdfdae8..f9be7b9 100644
--- a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
+++ b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
@@ -587,6 +587,7 @@
         final InetAddress neighB = InetAddresses.parseNumericAddress("2001:db8::2");
         final InetAddress neighLL = InetAddresses.parseNumericAddress("fe80::1");
         final InetAddress neighMC = InetAddresses.parseNumericAddress("ff02::1234");
+        final MacAddress macNull = MacAddress.fromString("00:00:00:00:00:00");
         final MacAddress macA = MacAddress.fromString("00:00:00:00:00:0a");
         final MacAddress macB = MacAddress.fromString("11:22:33:00:00:0b");
 
@@ -612,13 +613,14 @@
         verifyNoMoreInteractions(mNetd);
 
         // A neighbor that is no longer valid causes the rule to be removed.
-        recvNewNeigh(myIfindex, neighA, NUD_FAILED, macA);
-        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macA));
+        // NUD_FAILED events do not have a MAC address.
+        recvNewNeigh(myIfindex, neighA, NUD_FAILED, null);
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macNull));
         reset(mNetd);
 
         // A neighbor that is deleted causes the rule to be removed.
         recvDelNeigh(myIfindex, neighB, NUD_STALE, macB);
-        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macB));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macNull));
         reset(mNetd);
 
         // Upstream changes result in deleting and re-adding the rules.