diff --git a/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs b/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs
index 46e39ef35b..4e2b5f1c58 100644
--- a/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs
+++ b/OpenSim/Region/OptionalModules/World/NPC/Tests/NPCModuleTests.cs
@@ -87,7 +87,7 @@ namespace OpenSim.Region.OptionalModules.World.NPC.Tests
         public void TestMove()
         {
             TestHelper.InMethod();
-            log4net.Config.XmlConfigurator.Configure();
+//            log4net.Config.XmlConfigurator.Configure();
 
             IConfigSource config = new IniConfigSource();
 
@@ -106,6 +106,12 @@ namespace OpenSim.Region.OptionalModules.World.NPC.Tests
             ScenePresence npc = scene.GetScenePresence(npcId);
             Assert.That(npc.AbsolutePosition, Is.EqualTo(startPos));
 
+            // For now, we'll make the scene presence fly to simplify this test, but this needs to change.
+            npc.PhysicsActor.Flying = true;
+
+            scene.Update();
+            Assert.That(npc.AbsolutePosition, Is.EqualTo(startPos));
+
             // Not yet complete
         }
     }
diff --git a/OpenSim/Region/Physics/BasicPhysicsPlugin/BasicPhysicsScene.cs b/OpenSim/Region/Physics/BasicPhysicsPlugin/BasicPhysicsScene.cs
index 6c9d9aba1d..1ceed1a91d 100644
--- a/OpenSim/Region/Physics/BasicPhysicsPlugin/BasicPhysicsScene.cs
+++ b/OpenSim/Region/Physics/BasicPhysicsPlugin/BasicPhysicsScene.cs
@@ -123,11 +123,15 @@ namespace OpenSim.Region.Physics.BasicPhysicsPlugin
                     actorPosition.X = ((int)Constants.RegionSize - 0.1f);
                 }
 
-                float height = _heightMap[(int)actor.Position.Y * Constants.RegionSize + (int)actor.Position.X] + actor.Size.Z;
+                float terrainHeight = 0;
+                if (_heightMap != null)
+                    terrainHeight = _heightMap[(int)actor.Position.Y * Constants.RegionSize + (int)actor.Position.X];
+
+                float height = terrainHeight + actor.Size.Z;
+
                 if (actor.Flying)
                 {
-                    if (actor.Position.Z + (actor.Velocity.Z*timeStep) <
-                        _heightMap[(int)actor.Position.Y * Constants.RegionSize + (int)actor.Position.X] + 2)
+                    if (actor.Position.Z + (actor.Velocity.Z * timeStep) < terrainHeight + 2)
                     {
                         actorPosition.Z = height;
                         actorVelocity.Z = 0;
@@ -135,7 +139,7 @@ namespace OpenSim.Region.Physics.BasicPhysicsPlugin
                     }
                     else
                     {
-                        actorPosition.Z += actor.Velocity.Z*timeStep;
+                        actorPosition.Z += actor.Velocity.Z * timeStep;
                         actor.IsColliding = false;
                     }
                 }