diff --git a/src/CADShared/Runtime/Env.cs b/src/CADShared/Runtime/Env.cs
index 024eb5d45d3f3c49fa1583349ebfeaba8b5fdad8..fd7b3539acbad80ee637698bb1141c22b4508279 100644
--- a/src/CADShared/Runtime/Env.cs
+++ b/src/CADShared/Runtime/Env.cs
@@ -289,7 +289,7 @@ public static ObjectId GetDimblkId(DimblkType dimblk)
         var oldDimblk = Acaop.GetSystemVariable("dimblk");
         Dimblk = dimblk;
         var id = HostApplicationServices.WorkingDatabase.Dimblk;
-        Acaop.SetSystemVariable("dimblk", oldDimblk);
+        Acaop.SetSystemVariable("dimblk", string.IsNullOrWhiteSpace(oldDimblk.ToString())? "." : oldDimblk);
         return id;
     }