diff --git a/src/RhinoInside.Revit.External/DB/Extensions/GeometryObject.cs b/src/RhinoInside.Revit.External/DB/Extensions/GeometryObject.cs
index 4c3025852..93bb59afe 100644
--- a/src/RhinoInside.Revit.External/DB/Extensions/GeometryObject.cs
+++ b/src/RhinoInside.Revit.External/DB/Extensions/GeometryObject.cs
@@ -669,6 +669,7 @@ public static BoundingBoxXYZ GetBoundingBox(this GeometryObject geometry, Transf
             else
             {
               var bbox = element.GetTransformed(coordSystem.Inverse).GetBoundingBox();
+              if (bbox.IsNegative()) bbox = BoundingBoxXYZExtension.Empty;
               bbox.Transform = coordSystem;
               return bbox;
             }
@@ -690,6 +691,7 @@ public static BoundingBoxXYZ GetBoundingBox(this GeometryObject geometry, Transf
             else
             {
               var bbox = instance.GetSymbolGeometry(coordSystem.Inverse * instance.Transform).GetBoundingBox();
+              if (bbox.IsNegative()) bbox = BoundingBoxXYZExtension.Empty;
               bbox.Transform = coordSystem;
               return bbox;
             }
@@ -697,6 +699,7 @@ public static BoundingBoxXYZ GetBoundingBox(this GeometryObject geometry, Transf
           else
           {
             var bbox = instance.SymbolGeometry.GetBoundingBox();
+            if (bbox.IsNegative()) bbox = BoundingBoxXYZExtension.Empty;
             bbox.Transform = instance.Transform;
             return bbox;
           }
@@ -744,11 +747,11 @@ public static BoundingBoxXYZ GetBoundingBox(this GeometryObject geometry, Transf
         {
           if (!solid.Faces.IsEmpty)
           {
+            var bbox = BoundingBoxXYZExtension.Empty;
             if (coordSystem is object)
             {
               if (accurateSolid)
               {
-                var bbox = BoundingBoxXYZExtension.Empty;
                 bbox.Transform = coordSystem;
 
                 foreach (Face face in solid.Faces)
@@ -761,7 +764,10 @@ public static BoundingBoxXYZ GetBoundingBox(this GeometryObject geometry, Transf
               {
                 using (var transformed = SolidUtils.CreateTransformed(solid, coordSystem.Inverse))
                 {
-                  var (min, max, transform, bounds) = transformed.GetBoundingBox();
+                  bbox = transformed.GetBoundingBox();
+                  if (bbox.IsNegative()) bbox = BoundingBoxXYZExtension.Empty;
+
+                  var (min, max, transform, bounds) = bbox;
                   var (minX, minY, minZ) = transform.OfPoint(min);
                   var (maxX, maxY, maxZ) = transform.OfPoint(max);
 
@@ -774,7 +780,10 @@ public static BoundingBoxXYZ GetBoundingBox(this GeometryObject geometry, Transf
                 }
               }
             }
-            return solid.GetBoundingBox();
+
+            bbox = solid.GetBoundingBox();
+            if (bbox.IsNegative()) bbox = BoundingBoxXYZExtension.Empty;
+            return bbox;
           }
         }
         break;
diff --git a/src/RhinoInside.Revit/AssemblyResolver.cs b/src/RhinoInside.Revit/AssemblyResolver.cs
index 9fb023e26..dcb758c13 100644
--- a/src/RhinoInside.Revit/AssemblyResolver.cs
+++ b/src/RhinoInside.Revit/AssemblyResolver.cs
@@ -544,7 +544,8 @@ static Assembly GetRequestingAssembly()
       int f = 0;
       for (; f < frames.Length; ++f)
       {
-        var frameAssembly = frames[f].GetMethod().DeclaringType.Assembly;
+        var method = frames[f].GetMethod();
+        var frameAssembly = method.DeclaringType?.Assembly ?? method.Module?.Assembly;
         if (frameAssembly != callingAssembly)
           break;
       }
@@ -552,7 +553,8 @@ static Assembly GetRequestingAssembly()
       // Skip mscorlib
       for (; f < frames.Length; ++f)
       {
-        var frameAssembly = frames[f].GetMethod().DeclaringType.Assembly;
+        var method = frames[f].GetMethod();
+        var frameAssembly = method.DeclaringType?.Assembly ?? method.Module?.Assembly;
         if (frameAssembly != typeof(object).Assembly)
           return frameAssembly;
       }