diff --git a/Subsurface/Source/Items/Item.cs b/Subsurface/Source/Items/Item.cs
index 1cbe1e4ee..d1ca4175b 100644
--- a/Subsurface/Source/Items/Item.cs
+++ b/Subsurface/Source/Items/Item.cs
@@ -770,6 +770,8 @@ namespace Barotrauma
             
             if (body == null || !body.Enabled) return;
 
+            System.Diagnostics.Debug.Assert(body.FarseerBody.FixtureList != null);
+
             if (Math.Abs(body.LinearVelocity.X) > 0.01f || Math.Abs(body.LinearVelocity.Y) > 0.01f)
             {
                 Submarine prevSub = Submarine;
diff --git a/Subsurface/Source/Map/Lights/ConvexHull.cs b/Subsurface/Source/Map/Lights/ConvexHull.cs
index 7ab0bc15d..c48285988 100644
--- a/Subsurface/Source/Map/Lights/ConvexHull.cs
+++ b/Subsurface/Source/Map/Lights/ConvexHull.cs
@@ -44,13 +44,24 @@ namespace Barotrauma.Lights
 
     class ConvexHullList
     {
+        private List<ConvexHull> list;
+
         public readonly Submarine Submarine;
-        public List<ConvexHull> List;
+        public List<ConvexHull> List
+        {
+            get { return list; }
+            set
+            {
+                Debug.Assert(value != null);
+                Debug.Assert(!list.Contains(null));
+                list = value;
+            }
+        }
 
         public ConvexHullList(Submarine submarine)
         {
             Submarine = submarine;
-            List = new List<ConvexHull>();
+            list = new List<ConvexHull>();
         }
     }
 
diff --git a/Subsurface/Source/Map/Lights/LightSource.cs b/Subsurface/Source/Map/Lights/LightSource.cs
index 931c9455f..36f7dbd3b 100644
--- a/Subsurface/Source/Map/Lights/LightSource.cs
+++ b/Subsurface/Source/Map/Lights/LightSource.cs
@@ -164,15 +164,15 @@ namespace Barotrauma.Lights
         
         private List<ConvexHull> GetHullsInRange(Submarine sub)
         {
+            //find the current list of hulls in range
             var chList = hullsInRange.Find(x => x.Submarine == sub);
 
+            //not found -> create one
             if (chList == null)
             {
                 chList = new ConvexHullList(sub);
                 hullsInRange.Add(chList);
             }
-            List<ConvexHull> list = chList.List;
-
 
             Vector2 lightPos = position;
             if (ParentSub == null)
@@ -183,15 +183,12 @@ namespace Barotrauma.Lights
                     if (NeedsHullUpdate)
                     {
                         var fullChList = ConvexHull.HullLists.Find(x => x.Submarine == sub);
-
-                        list = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
-                        chList.List = list;
+                        chList.List = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
                     }
                 }
                 //light is outside, convexhull inside a sub
                 else
                 {
-                    //todo: check
                     lightPos -= sub.Position;
 
                     Rectangle subBorders = sub.Borders;
@@ -201,7 +198,7 @@ namespace Barotrauma.Lights
                     if (!MathUtils.CircleIntersectsRectangle(lightPos, range, subBorders)) return null;
 
                     var fullChList = ConvexHull.HullLists.Find(x => x.Submarine == sub);
-                    list = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
+                    chList.List = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
                 }
             }
             else 
@@ -215,15 +212,13 @@ namespace Barotrauma.Lights
                     if (NeedsHullUpdate)
                     {
                         var fullChList = ConvexHull.HullLists.Find(x => x.Submarine == sub);
-
-                        list = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
-                        chList.List = list;
+                        chList.List = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
                     }
                 }
                 //light and convexhull are inside different subs
                 else
                 {
-                    if (sub.DockedTo.Contains(ParentSub) && !NeedsHullUpdate) return list;
+                    if (sub.DockedTo.Contains(ParentSub) && !NeedsHullUpdate) return chList.List;
 
                     lightPos -= (sub.Position - ParentSub.Position);
 
@@ -234,12 +229,11 @@ namespace Barotrauma.Lights
                     if (!MathUtils.CircleIntersectsRectangle(lightPos, range, subBorders)) return null;
 
                     var fullChList = ConvexHull.HullLists.Find(x => x.Submarine == sub);
-                    list = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
-                    chList.List = list;
+                    chList.List = fullChList.List.FindAll(ch => MathUtils.CircleIntersectsRectangle(lightPos, range, ch.BoundingBox));
                 }
             }
 
-            return list;
+            return chList.List;
         }
 
         public static List<ConvexHull> GetHullsInRange(Vector2 position, float range, Submarine ParentSub)