diff --git a/elaborate.cc b/elaborate.cc
index f22e38f00..ad7c273ab 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -944,6 +944,17 @@ NetNet*PGModule::resize_net_to_port_(Design*des, NetScope*scope,
       return tmp;
 }
 
+static bool need_bufz_for_input_port(const svector<NetNet*>&prts)
+{
+      if (prts[0]->port_type() != NetNet::PINPUT)
+	    return false;
+
+      if (prts[0]->pin(0).nexus()->drivers_present())
+	    return true;
+
+      return false;
+}
+
 /*
  * Instantiate a module by recursively elaborating it. Set the path of
  * the recursive elaboration so that signal names get properly
@@ -1162,7 +1173,7 @@ void PGModule::elaborate_mod_(Design*des, Module*rmod, NetScope*scope) const
 		       width. We use that, then, to decide how to hook
 		       it up.
 
-		       NOTE that this also handles the case that the
+v		       NOTE that this also handles the case that the
 		       port is actually empty on the inside. We assume
 		       in that case that the port is input. */
 
@@ -1176,6 +1187,21 @@ void PGModule::elaborate_mod_(Design*des, Module*rmod, NetScope*scope) const
 			continue;
 		  }
 
+		  if (need_bufz_for_input_port(prts)) {
+			NetBUFZ*tmp = new NetBUFZ(scope, scope->local_symbol(),
+						  sig->vector_width());
+			des->add_node(tmp);
+			connect(tmp->pin(1), sig->pin(0));
+
+			NetNet*tmp2 = new NetNet(scope, scope->local_symbol(),
+						 NetNet::WIRE, sig->vector_width());
+			tmp2->local_flag(true);
+			tmp2->set_line(*this);
+			tmp2->data_type(sig->data_type());
+			connect(tmp->pin(0), tmp2->pin(0));
+			sig = tmp2;
+		  }
+
 	    } else if (prts[0]->port_type() == NetNet::PINOUT) {
 
 		    /* Inout to/from module. This is a more
diff --git a/net_link.cc b/net_link.cc
index 228add8c0..5b2621b90 100644
--- a/net_link.cc
+++ b/net_link.cc
@@ -247,6 +247,41 @@ verinum::V Nexus::get_init() const
       return verinum::Vz;
 }
 
+bool Nexus::drivers_present() const
+{
+      assert(list_);
+      for (Link*cur = list_ ;  cur ; cur = cur->next_) {
+	    if (cur->get_dir() == Link::OUTPUT)
+		  return true;
+
+	    if (cur->get_dir() == Link::INPUT)
+		  continue;
+
+	      // Must be PASSIVE, so if it is some kind of net, see if
+	      // it is the sort that might drive the nexus.
+	    const NetObj*obj;
+	    unsigned pin;
+	    cur->cur_link(obj, pin);
+	    if (const NetNet*net = dynamic_cast<const NetNet*>(obj))
+		  switch (net->type()) {
+		      case NetNet::SUPPLY0:
+		      case NetNet::SUPPLY1:
+		      case NetNet::TRI0:
+		      case NetNet::TRI1:
+		      case NetNet::WAND:
+		      case NetNet::WOR:
+		      case NetNet::TRIAND:
+		      case NetNet::TRIOR:
+		      case NetNet::REG:
+			return true;
+		      default:
+			break;
+		  }
+      }
+
+      return false;
+}
+
 void Nexus::drivers_delays(NetExpr*rise, NetExpr*fall, NetExpr*decay)
 {
       for (Link*cur = list_ ; cur ; cur = cur->next_) {
diff --git a/netlist.h b/netlist.h
index d6e01bab2..7818938e8 100644
--- a/netlist.h
+++ b/netlist.h
@@ -290,6 +290,10 @@ class Nexus {
 
       NetNet* pick_any_net();
 
+	/* This method returns true if there are any drivers
+	   (including variables) attached to this nexus. */
+      bool drivers_present() const;
+
 	/* This method returns true if all the possible drivers of
 	   this nexus are constant. It will also return true if there
 	   are no drivers at all. */