diff --git a/OpenSim/Region/Application/OpenSim.cs b/OpenSim/Region/Application/OpenSim.cs
index b24641a454..2236e4388a 100644
--- a/OpenSim/Region/Application/OpenSim.cs
+++ b/OpenSim/Region/Application/OpenSim.cs
@@ -1111,7 +1111,7 @@ namespace OpenSim
                             aCircuit.Name,
                             aCircuit.child ? "child" : "root",
                             aCircuit.circuitcode.ToString(),
-                            aCircuit.IPAddress.ToString(),
+                            aCircuit.IPAddress != null ? aCircuit.IPAddress.ToString() : "not set",
                             aCircuit.Viewer);
                 });
 
diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index 2cdc4b301d..7d8cbf5804 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -3384,9 +3384,10 @@ namespace OpenSim.Region.Framework.Scenes
                 }
                 else
                 {
-                    // We remove the acd up here to avoid later raec conditions if two RemoveClient() calls occurred
+                    // We remove the acd up here to avoid later race conditions if two RemoveClient() calls occurred
                     // simultaneously.
-                    m_authenticateHandler.RemoveCircuit(acd.circuitcode);
+                    // We also need to remove by agent ID since NPCs will have no circuit code.
+                    m_authenticateHandler.RemoveCircuit(agentID);
                 }
             }
 
diff --git a/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs b/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs
index 91799667ab..52ed8468c6 100644
--- a/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs
+++ b/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs
@@ -117,6 +117,12 @@ namespace OpenSim.Region.OptionalModules.World.NPC.Tests
             Assert.That(npc, Is.Not.Null);
             Assert.That(npc.Appearance.Texture.FaceTextures[8].TextureID, Is.EqualTo(originalFace8TextureId));
             Assert.That(m_umMod.GetUserName(npc.UUID), Is.EqualTo(string.Format("{0} {1}", npc.Firstname, npc.Lastname)));
+
+            IClientAPI client;
+            Assert.That(m_scene.TryGetClient(npcId, out client), Is.True);
+
+            // Have to account for both SP and NPC.
+            Assert.That(m_scene.AuthenticateHandler.GetAgentCircuits().Count, Is.EqualTo(2));
         }
 
         [Test]
@@ -136,6 +142,11 @@ namespace OpenSim.Region.OptionalModules.World.NPC.Tests
             ScenePresence deletedNpc = m_scene.GetScenePresence(npcId);
 
             Assert.That(deletedNpc, Is.Null);
+            IClientAPI client;
+            Assert.That(m_scene.TryGetClient(npcId, out client), Is.False);
+
+            // Have to account for SP still present.
+            Assert.That(m_scene.AuthenticateHandler.GetAgentCircuits().Count, Is.EqualTo(1));
         }
 
         [Test]