diff --git a/src/include/maskfld.cpp b/src/include/maskfld.cpp
index aefa3f9a2..1bda846b6 100755
--- a/src/include/maskfld.cpp
+++ b/src/include/maskfld.cpp
@@ -579,11 +579,10 @@ void TMask_field::show(
       if (s != nullptr)
       {
         const int nrow = s->selected();
+        int id = dlg();
 
-        if (nrow >= 0 && nrow < s->items() && s->exist_column(dlg()))
+        if (nrow >= 0 && nrow < s->items() && id >= 0 && s->exist_column(dlg()))
         {
-          int id = dlg();
-
           for (int pos = mask().first_cell_fldpos(id); pos >= 0; pos = mask().next_cell_fldpos(id))
             if (mask().fld(pos).shown())
             {
diff --git a/src/include/msksheet.cpp b/src/include/msksheet.cpp
index 93b018664..f67b88e69 100755
--- a/src/include/msksheet.cpp
+++ b/src/include/msksheet.cpp
@@ -2214,6 +2214,7 @@ void TSpreadsheet::enable_cell(
     column = cid2index(column);
 
   TRow_property* prop = get_property(row);
+
   if (prop == NULL)
   {
     if (on) return;   // Don't waste time and memory