diff --git a/base/netcmp.c b/base/netcmp.c
index 8fa533e..35c0bf9 100644
--- a/base/netcmp.c
+++ b/base/netcmp.c
@@ -4551,13 +4551,13 @@ int EquivalenceNodes(char *name1, int file1, char *name2, int file2)
 /* database.						*/
 /*------------------------------------------------------*/
 
-int IgnoreClass(char *name, int file)
+int IgnoreClass(char *name, int file, unsigned char type)
 {
    struct IgnoreList *newIgnore;
 
    if ((file == -1) && (Circuit1 != NULL) && (Circuit2 != NULL)) {
-      IgnoreClass(name, Circuit1->file);
-      IgnoreClass(name, Circuit2->file);
+      IgnoreClass(name, Circuit1->file, type);
+      IgnoreClass(name, Circuit2->file, type);
       return;
    }
 
@@ -4567,9 +4567,13 @@ int IgnoreClass(char *name, int file)
    newIgnore->class = (char *)MALLOC(1 + strlen(name));
    strcpy(newIgnore->class, name);
    newIgnore->file = file;
+   newIgnore->type = type;
 
    /* Remove existing classes from database */
-   ClassDelete(name, file);
+   if (type == IGNORE_CLASS)
+      ClassDelete(name, file);
+   else
+      RemoveShorted(name, file);
 
    return 0;
 }
diff --git a/base/netcmp.h b/base/netcmp.h
index 240e822..e8daa42 100644
--- a/base/netcmp.h
+++ b/base/netcmp.h
@@ -32,7 +32,7 @@ extern int PermuteForget(char *model, int filenum, char *pin1, char *pin2);
 extern int EquivalenceElements(char *name1, int file1, char *name2, int file2);
 extern int EquivalenceNodes(char *name1, int file1, char *name2, int file2);
 extern int EquivalenceClasses(char *name1, int file1, char *name2, int file2);
-extern int IgnoreClass(char *name, int file);
+extern int IgnoreClass(char *name, int file, unsigned char type);
 extern int MatchPins(struct nlist *tp1, struct nlist *tp2);
 
 extern int  CreateCompareQueue(char *, int, char *, int);
diff --git a/base/netgen.c b/base/netgen.c
index b1b24a6..aee2446 100644
--- a/base/netgen.c
+++ b/base/netgen.c
@@ -1212,6 +1212,10 @@ void CellDefNoCase(char *name, int file)
    CurrentCell->flags |= CELL_NOCASE;
 }
 
+/*----------------------------------------------------------------------*/
+/* Return 0 if class 'name' is not being ignored (per the 'ignore'	*/
+/* command);  1 if it is ignored, and 2 if shorted instances should be	*/
+/* ignored.								*/
 /*----------------------------------------------------------------------*/
 
 int IsIgnored(char *name, int file)
@@ -1223,7 +1227,7 @@ int IsIgnored(char *name, int file)
     {
 	if ((file == -1) || (ilist->file == -1) || (file == ilist->file)) 
 	    if ((*matchfunc)(ilist->class, nptr))
-		return 1;
+		return ilist->type;	/* IGNORE_CLASS or IGNORE_SHORTED */
     }
    return 0;
 }
@@ -1361,10 +1365,6 @@ void Instance(char *model, char *instancename)
     return;
   }
   fnum = CurrentCell->file;
-  if (IsIgnored(model, fnum)) {
-    Printf("Class '%s' instanced in input but is being ignored.\n", model);
-    return;
-  }
   instanced_cell = LookupCellFile(model, fnum);
   if (instanced_cell == NULL) {
     Printf("Attempt to instance undefined model '%s'\n", model);
@@ -1504,7 +1504,7 @@ char *Cell(char *inststr, char *model, ...)
   struct objlist *namedporthead, *namedportp, *namedlisthead, *namedlistp;
   int portnum, portlist, done;
   char namedport[512]; /* tmp buffers */
-  int filenum;
+  int filenum, itype, samenode;
 
   static char *instancename = NULL;
   char *instnameptr;
@@ -1517,7 +1517,7 @@ char *Cell(char *inststr, char *model, ...)
      filenum = CurrentCell->file;
 	
   if (Debug) Printf("   calling cell: %s\n",model);
-  if (IsIgnored(model, filenum)) {
+  if ((itype = IsIgnored(model, filenum)) == IGNORE_CLASS) {
     Printf("Class '%s' instanced in input but is being ignored.\n", model);
     return NULL;
   }
@@ -1600,6 +1600,21 @@ char *Cell(char *inststr, char *model, ...)
   }
   va_end(ap);
 
+  /* Check for shorted pins */
+  if ((itype == IGNORE_SHORTED) && (head != NULL)) {
+     unsigned char shorted = (unsigned char)1;
+     for (tp = head->next; tp; tp = tp->next) {
+        if (strcasecmp(head->name, tp->name))
+           shorted = (unsigned char)0;
+           break;
+     }
+     if (shorted == (unsigned char)1) {
+        Printf("Instance of '%s' is shorted, ignoring.\n", model);
+        FreeObject(head);
+        return NULL;
+     }
+  }
+
   if (inststr == NULL) {
     if (instancename != NULL)
        FreeString(instancename);
@@ -1992,7 +2007,7 @@ struct objlist *LinkProperties(char *model, struct keyvalue *topptr)
     else
 	filenum = CurrentCell->file;
 
-    if (IsIgnored(model, filenum)) {
+    if (IsIgnored(model, filenum) == IGNORE_CLASS) {
 	Printf("Class '%s' instanced in input but is being ignored.\n", model);
 	return NULL;
     }
diff --git a/base/objlist.c b/base/objlist.c
index dd28cc7..9ddd032 100644
--- a/base/objlist.c
+++ b/base/objlist.c
@@ -340,6 +340,71 @@ void CellRehash(char *name, char *newname, int file)
 
 struct nlist *OldCell;
 
+int removeshorted(struct hashlist *p, int file)
+{
+   struct nlist *ptr;
+   struct objlist *ob, *lob, *nob, *tob;
+   unsigned char shorted;
+
+   ptr = (struct nlist *)(p->ptr);
+
+   if ((file != -1) && (ptr->file != file)) return;
+
+   lob = NULL;
+   for (ob = ptr->cell; ob != NULL;) {
+      nob = ob->next;
+      if ((ob->type == FIRSTPIN) && (ob->model.class != NULL)) {
+	 if ((*matchfunc)(ob->model.class, OldCell->name)) {
+            shorted = (unsigned char)1;
+	    for (tob = nob; tob->type > FIRSTPIN; tob = tob->next) {
+	       if (tob->node != ob->node) {
+	           shorted = (unsigned char)0;
+	           break;
+	       }
+            }
+	    if (shorted == (unsigned char)0) {
+               lob = ob;
+               ob = nob;
+	       continue;
+	    }
+	    HashDelete(ob->instance.name, &(ptr->instdict));
+	    while (1) {
+	       FreeObjectAndHash(ob, ptr);
+	       ob = nob;
+	       if (ob == NULL) break;
+	       nob = ob->next;
+	       if (ob->type != PROPERTY && ob->type <= FIRSTPIN) break;
+	    }
+	    if (lob == NULL)
+	       ptr->cell = ob;
+	    else
+	       lob->next = ob;
+	 }
+	 else {
+	    lob = ob;
+	    ob = nob;
+	 }
+      }
+      else {
+         lob = ob;
+         ob = nob;
+      }
+   }
+}
+
+/* Remove shorted instances of class "class" from the database */
+
+void RemoveShorted(char *class, int file)
+{
+   if (file == -1)
+      OldCell = LookupCell(class);
+   else
+      OldCell = LookupCellFile(class, file);
+
+   if (OldCell == NULL) return;
+   RecurseCellFileHashTable(removeshorted, file);
+}
+
 int deleteclass(struct hashlist *p, int file)
 {
    struct nlist *ptr;
diff --git a/base/objlist.h b/base/objlist.h
index 1794c7c..d852e99 100644
--- a/base/objlist.h
+++ b/base/objlist.h
@@ -159,9 +159,16 @@ extern struct objlist *LastPlaced;
 struct IgnoreList {
     char *class;
     int file;
+    unsigned char type;
     struct IgnoreList *next;
 };
 
+/* Types used by IgnoreList above */
+
+#define IGNORE_NONE	(unsigned char)0
+#define IGNORE_CLASS	(unsigned char)1
+#define IGNORE_SHORTED	(unsigned char)2
+
 /* Record structure for handling pin permutations in a cell	*/
 /* Linked list structure allows multiple permutations per cell.	*/
 
diff --git a/base/spice.c b/base/spice.c
index 12ff209..2a6d438 100644
--- a/base/spice.c
+++ b/base/spice.c
@@ -1530,6 +1530,8 @@ skip_ends:
 
     else if (toupper(nexttok[0]) == 'X') {	/* subcircuit instances */
       char instancename[100], subcktname[100];
+      int itype;
+
       instancename[99] = '\0';
       subcktname[99] = '\0';
 
@@ -1602,6 +1604,34 @@ skip_ends:
       if (scan->next != NULL) scan = scan->next;
       tail->next = NULL;
 
+      /* Check for ignored class */
+
+      if ((itype = IsIgnored(subcktname, filenum)) == IGNORE_CLASS) {
+          Printf("Class '%s' instanced in input but is being ignored.\n", model);
+          return;
+      }
+
+      /* Check for shorted pins */
+
+      if ((itype == IGNORE_SHORTED) && (head != NULL)) {
+         unsigned char shorted = (unsigned char)1;
+         struct portelement *p;
+         for (p = head->next; p; p = p->next) {
+            if (strcasecmp(head->name, p->name))
+               shorted = (unsigned char)0;
+               break;
+         }
+         if (shorted == (unsigned char)1) {
+            Printf("Instance of '%s' is shorted, ignoring.\n", subcktname);
+	    while (head) {
+	       p = head->next;
+	       FREE(head);
+	       head = p;
+            }
+            return;
+         }
+      }
+
       /* Create cell name and revise instance name based on the cell name */
       /* For clarity, if "instancename" does not contain the cellname,	  */
       /* then prepend the cellname to the instance name.  HOWEVER, if any */
@@ -1658,6 +1688,7 @@ skip_ends:
       }
 
       /* nexttok is now NULL, scan->name points to class */
+
       Instance(subcktname, instancename);
       pobj = LinkProperties(subcktname, kvlist);
       ReduceExpressions(pobj, NULL, CurrentCell, TRUE);
diff --git a/tcltk/tclnetgen.c b/tcltk/tclnetgen.c
index c7e480f..89293b9 100644
--- a/tcltk/tclnetgen.c
+++ b/tcltk/tclnetgen.c
@@ -2518,10 +2518,10 @@ _netcmp_ignore(ClientData clientData,
     Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[])
 {
    char *options[] = {
-      "class", NULL
+      "class", "shorted", NULL
    };
    enum OptionIdx {
-      CLASS_IDX
+      CLASS_IDX, SHORTED_IDX
    };
    int result, index;
    int file = -1;
@@ -2542,7 +2542,14 @@ _netcmp_ignore(ClientData clientData,
       Tcl_WrongNumArgs(interp, 1, objv, "[class] valid_cellname");
       return TCL_ERROR;
    }
-   IgnoreClass(name, file);
+   switch (index) {
+      case CLASS_IDX:
+         IgnoreClass(name, file, IGNORE_CLASS);
+	 break;
+      case SHORTED_IDX:
+         IgnoreClass(name, file, IGNORE_SHORTED);
+	 break;
+   }
    return TCL_OK;
 }