diff --git a/VERSION b/VERSION
index 8823545..274b8fb 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.5.170
+1.5.171
diff --git a/base/netcmp.c b/base/netcmp.c
index 962aa18..6f48f86 100644
--- a/base/netcmp.c
+++ b/base/netcmp.c
@@ -5363,13 +5363,21 @@ PropertyMatch(struct objlist *ob1, int file1,
    /* WIP---Check for no-connect pins in merged devices on both sides.	*/
    /* Both sides should either have no-connects marked, or neither.	*/
    /* (Permutable pins may need to be handled correctly. . .		*/
+
    for (tp1 = ob1, tp2 = ob2; (tp1 != NULL) && tp1->type >= FIRSTPIN &&
 	    (tp2 != NULL) && tp2->type >= FIRSTPIN; tp1 = tp1->next, tp2 = tp2->next)
    {
       struct objlist *node1, *node2;
 
-      node1 = Circuit1->nodename_cache[tp1->node];
-      node2 = Circuit2->nodename_cache[tp2->node];
+      if (file1 == Circuit1->file)
+	 node1 = Circuit1->nodename_cache[tp1->node];
+      else
+	 node1 = Circuit2->nodename_cache[tp1->node];
+
+      if (file2 == Circuit1->file)
+         node2 = Circuit1->nodename_cache[tp2->node];
+      else
+         node2 = Circuit2->nodename_cache[tp2->node];
 
       if (node1->instance.flags != node2->instance.flags)
       {
diff --git a/tcltk/netgen.tcl.in b/tcltk/netgen.tcl.in
index 431bcf1..e3ac928 100644
--- a/tcltk/netgen.tcl.in
+++ b/tcltk/netgen.tcl.in
@@ -352,7 +352,7 @@ proc netgen::convert_to_json {filename lvs_final} {
    close $fjson
 }
 
-#----------------------------------------------------------------
+#-----------------------------------------------------------------------
 # Define the "lvs" command as a way of calling the netgen options
 # for standard compare, essentially the same as the old "netcomp"
 # standalone program.
@@ -361,14 +361,20 @@ proc netgen::convert_to_json {filename lvs_final} {
 # although if the cells have not been read in yet, then the
 # original syntax of filename or {filename cellname} is required.
 #
-# "args" is passed to verify and may therefore contain only the
-# value "-list" or nothing.  If "-list", then output is returned
-# as a nested list.
-#----------------------------------------------------------------
+# "args" may be "-list", "-json", or "-blackbox".
+#    "-list" returns output as a nested list.
+#    "-json" creates a .json-format output file in addition to stdout.
+#    "-blackbox" treats empty cells as black-box entries.
+#    "-noflatten={list}" is a list of cells not to flatten if mismatched.
+#    i.e., the cells are expected to match and any mismatch cannot be
+#    expected to be resolved by flattening the contents of the mismatched
+#    cells.
+#-----------------------------------------------------------------------
 
 proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
    set dolist 0
    set dojson 0
+   set noflat {}
    foreach arg $args {
       if {$arg == "-list"} {
 	 puts stdout "Generating list result"
@@ -382,6 +388,9 @@ proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
       } elseif {$arg == "-blackbox"} {
 	 puts stdout "Treating empty subcircuits as black-box cells"
 	 netgen::model blackbox on
+      } elseif {[string first "-noflatten=" $arg] == 0} {
+	 set noflat [string trim [string range $arg 11 end] \"\{\}]
+	 puts stdout "Will not flatten these subcells: $noflat"
       }
    }
 
@@ -501,6 +510,7 @@ proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
       return
    }
    set properr {}
+   set matcherr {}
    set pinsgood 0
    while {$endval != {}} {
       if {$dolist == 1} {
@@ -529,9 +539,30 @@ proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
 
 	    # Flatten the non-matching subcircuit (but not the top-level cells)
             if {[netgen::print queue] != {}} {
-	       netgen::log put "  Flattening non-matched subcircuits $endval"
-	       netgen::flatten class "[lindex $endval 0] $fnum1"
-	       netgen::flatten class "[lindex $endval 1] $fnum2"
+	       if {([lsearch $noflat [lindex $endval 0]] == -1) &&
+			([lsearch $noflat [lindex $endval 1]] == -1)} {
+	           netgen::log put "  Flattening non-matched subcircuits $endval"
+	           netgen::flatten class "[lindex $endval 0] $fnum1"
+	           netgen::flatten class "[lindex $endval 1] $fnum2"
+	       } else {
+	           netgen::log put "  Continuing with black-boxed subcircuits $endval"
+		   lappend matcherr [lindex $endval 0]
+	           # Match pins
+                   netgen::log echo off
+	           if {$dolist == 1} {
+		       set result [equate -list -force pins "$fnum1 [lindex $endval 0]" \
+				"$fnum2 [lindex $endval 1]"]
+	           } else {
+		       set result [equate -force pins "$fnum1 [lindex $endval 0]" \
+				"$fnum2 [lindex $endval 1]"]
+	           }
+	           if {$result != 0} {
+		       equate classes "$fnum1 [lindex $endval 0]" \
+			        "$fnum2 [lindex $endval 1]"
+	           }
+	           set pinsgood $result
+                   netgen::log echo on
+	       }
 	    }
 	 } else {
 	    # Match pins
@@ -554,9 +585,32 @@ proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
       } else {
 	 # Flatten the non-matching subcircuit (but not the top-level cells)
          if {[netgen::print queue] != {}} {
-	    netgen::log put "  Flattening non-matched subcircuits $endval"
-	    netgen::flatten class "[lindex $endval 0] $fnum1"
-	    netgen::flatten class "[lindex $endval 1] $fnum2"
+	    if {([lsearch $noflat [lindex $endval 1]] == -1) &&
+		    ([lsearch $noflat [lindex $endval 1]] == -1)} {
+	       netgen::log put "  Flattening non-matched subcircuits $endval"
+	       netgen::flatten class "[lindex $endval 0] $fnum1"
+	       netgen::flatten class "[lindex $endval 1] $fnum2"
+	    } else {
+	       netgen::log put "  Continuing with black-boxed subcircuits $endval"
+	       lappend matcherr [lindex $endval 0]
+	       netgen::log put "  Continuing with black-boxed subcircuits $endval"
+	       lappend matcherr [lindex $endval 0]
+	       # Match pins
+               netgen::log echo off
+	       if {$dolist == 1} {
+		   set result [equate -list -force pins "$fnum1 [lindex $endval 0]" \
+			    "$fnum2 [lindex $endval 1]"]
+	       } else {
+		   set result [equate -force pins "$fnum1 [lindex $endval 0]" \
+			    "$fnum2 [lindex $endval 1]"]
+	       }
+	       if {$result != 0} {
+		   equate classes "$fnum1 [lindex $endval 0]" \
+			    "$fnum2 [lindex $endval 1]"
+	       }
+	       set pinsgood $result
+               netgen::log echo on
+	    }
 	 }
       }
       netgen::log echo off
@@ -579,6 +633,9 @@ proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
    if {$properr != {}} {
       netgen::log put "The following cells had property errors: $properr\n"
    }
+   if {$matcherr != {}} {
+      netgen::log put "The following subcells failed to match: $matcherr\n"
+   }
    if {$dolog} {
       netgen::log end
    }
diff --git a/tcltk/tclnetgen.c b/tcltk/tclnetgen.c
index e34522f..ccab280 100644
--- a/tcltk/tclnetgen.c
+++ b/tcltk/tclnetgen.c
@@ -2827,11 +2827,13 @@ _netcmp_equate(ClientData clientData,
    char *name1 = NULL, *name2 = NULL, *optstart;
    struct nlist *tp1, *tp2, *SaveC1, *SaveC2;
    struct objlist *ob1, *ob2;
+   struct ElementClass *saveEclass = NULL;
+   struct NodeClass *saveNclass = NULL;
    int file1, file2;
-   int i, l1, l2, ltest, lent, dolist = 0;
+   int i, l1, l2, ltest, lent, dolist = 0, doforce = 0;
    Tcl_Obj *tobj1, *tobj2, *tobj3;
 
-   if (objc > 1) {
+   while (objc > 1) {
       optstart = Tcl_GetString(objv[1]);
       if (*optstart == '-') optstart++;
       if (!strcmp(optstart, "list")) {
@@ -2839,6 +2841,13 @@ _netcmp_equate(ClientData clientData,
 	 objv++;
 	 objc--;
       }
+      else if (!strcmp(optstart, "force")) {
+	 doforce = 1;
+	 objv++;
+	 objc--;
+      }
+      else
+	 break;
    }
 
    if ((objc != 2) && (objc != 4) && (objc != 6)) {
@@ -2996,6 +3005,12 @@ _netcmp_equate(ClientData clientData,
 	 break;
 
       case PINS_IDX:
+	 if ((ElementClasses != NULL) && (doforce == TRUE)) {
+	    saveEclass = ElementClasses;
+	    saveNclass = NodeClasses;
+	    ElementClasses = NULL;
+	    NodeClasses = NULL;
+	 }
 	 if ((ElementClasses == NULL) && (auto_blackbox == FALSE)) {
 	    if (CurrentCell == NULL) {
 		Fprintf(stderr, "Equate elements:  no current cell.\n");
@@ -3058,6 +3073,12 @@ _netcmp_equate(ClientData clientData,
 	    /* Recover temporarily set global variables (see above) */
 	    Circuit1 = SaveC1;
 	    Circuit2 = SaveC2;
+
+	    /* Recover ElementClasses if forcing pins on mismatched circuits */
+	    if (doforce == TRUE) {
+	       ElementClasses = saveEclass;
+	       NodeClasses = saveNclass;
+	    }
 	 }
 	 break;