diff --git a/VERSION b/VERSION
index 8ace87ff..3acdebd0 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-8.3.220
+8.3.221
diff --git a/lef/defWrite.c b/lef/defWrite.c
index e9dbae77..fcba26d2 100644
--- a/lef/defWrite.c
+++ b/lef/defWrite.c
@@ -695,6 +695,9 @@ defnodeVisit(node, res, cap, defdata)
     TTMaskZero(&tmask);
     TTMaskSetMask(&tmask, &DBConnectTbl[magictype]);
 
+    /* Avoid attempting to extract an implicit substrate into DEF */
+    if (node->efnode_type == TT_SPACE) return 0;
+
     DBSrConnect(def, &node->efnode_loc, &tmask, DBConnectTbl,
 		&TiPlaneRect, defNetGeometryFunc,
 		(ClientData)defdata);
diff --git a/select/selEnum.c b/select/selEnum.c
index 7f0529b7..05c31a16 100644
--- a/select/selEnum.c
+++ b/select/selEnum.c
@@ -149,6 +149,9 @@ SelEnumPaint(layers, editOnly, foundNonEdit, func, clientData)
     arg.sea_rectList = NULL;
     if (foundNonEdit != NULL) *foundNonEdit = FALSE;
 
+    /* EditCellUse is referenced in selEnumPFunc1() and must be non-NULL */
+    if (EditCellUse == NULL) return 1;
+
     /* First, find all the paint in the selection that has the right
      * layers.  Use the same procedure as "dbCellUniqueTileSrFunc()"
      * so that contacts are not double-counted.
diff --git a/select/selOps.c b/select/selOps.c
index e71ed7ce..1b7089ee 100644
--- a/select/selOps.c
+++ b/select/selOps.c
@@ -103,6 +103,11 @@ SelectDelete(msg, do_clear)
 
     extern int selDelPaintFunc(), selDelCellFunc(), selDelLabelFunc();
 
+    if (EditCellUse == NULL)
+    {
+	TxError("The current cell is not editable.\n");
+	return;
+    }
     (void) SelEnumPaint(&DBAllButSpaceAndDRCBits, TRUE, &nonEdit,
 	    selDelPaintFunc, (ClientData) NULL);
     if (nonEdit)
@@ -964,6 +969,11 @@ SelectTransform(transform)
 					 * visible) coordinates.
 					 */
 {
+    if (EditCellUse == NULL)
+    {
+	TxError("The current cell is not editable.\n");
+	return;
+    }
 
     /* Copy from SelectDef to Select2Def, transforming along the way. */