diff --git a/elab_expr.cc b/elab_expr.cc
index 5edcf1a3b..4c22f9c6b 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -163,15 +163,11 @@ unsigned PExpr::test_width(Design*des, NetScope*, width_mode_t&)
       return 1;
 }
 
-NetExpr* PExpr::elaborate_expr(Design*des, NetScope*, ivl_type_t, unsigned) const
+NetExpr* PExpr::elaborate_expr(Design*des, NetScope*scope, ivl_type_t, unsigned flags) const
 {
-      cerr << get_fileline() << ": internal error: I do not know how to"
-	   << " elaborate (ivl_type_t) this expression. " << endl;
-      cerr << get_fileline() << ":               : Expression is: " << *this
-	   << endl;
-      cerr << get_fileline() << ":               : Expression type: " << typeid(*this).name() << endl;
-      des->errors += 1;
-      return 0;
+	// Fall back to the old method. Currently the new method won't be used
+	// if the target is a vector type, so we can use an arbitrary width.
+      return elaborate_expr(des, scope, 1, flags);
 }
 
 
@@ -181,6 +177,7 @@ NetExpr* PExpr::elaborate_expr(Design*des, NetScope*, unsigned, unsigned) const
 	   << " elaborate this expression. " << endl;
       cerr << get_fileline() << ":               : Expression is: " << *this
 	   << endl;
+      cerr << get_fileline() << ":               : Expression type: " << typeid(*this).name() << endl;
       des->errors += 1;
       return 0;
 }
diff --git a/elaborate.cc b/elaborate.cc
index 5af51cc64..25a4b979f 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -2317,7 +2317,7 @@ NetExpr* PAssign_::elaborate_rval_(Design*des, NetScope*scope,
 {
       ivl_assert(*this, rval_);
 
-      NetExpr*rv = rval_->elaborate_expr(des, scope, net_type, 0);
+      NetExpr*rv = elab_and_eval(des, scope, rval_, net_type, is_constant_);
 
       if (!is_constant_ || !rv) return rv;
 
diff --git a/netmisc.cc b/netmisc.cc
index f9e9a8b44..450eb6c05 100644
--- a/netmisc.cc
+++ b/netmisc.cc
@@ -1011,6 +1011,36 @@ NetExpr* elab_and_eval(Design*des, NetScope*scope, PExpr*pe,
             flags |= PExpr::NEED_CONST;
 
       NetExpr*tmp = pe->elaborate_expr(des, scope, lv_net_type, flags);
+      if (tmp == 0) return 0;
+
+      ivl_variable_type_t cast_type = ivl_type_base(lv_net_type);
+      if ((cast_type != IVL_VT_NO_TYPE) && (cast_type != tmp->expr_type())) {
+	      // Catch some special cases.
+	    switch (cast_type) {
+		case IVL_VT_DARRAY:
+		case IVL_VT_QUEUE:
+		  if (dynamic_cast<PEAssignPattern*>(pe))
+			return tmp;
+		  // fall through
+		case IVL_VT_STRING:
+		  if (dynamic_cast<PEConcat*>(pe))
+			return tmp;
+		  break;
+		case IVL_VT_CLASS:
+		  if (dynamic_cast<PENull*>(pe))
+			return tmp;
+		  break;
+		default:
+		  break;
+	    }
+
+	    cerr << tmp->get_fileline() << ": error: "
+		    "The expression '" << *pe << "' cannot be implicitly "
+		    "cast to the target type." << endl;
+	    des->errors += 1;
+	    delete tmp;
+	    return 0;
+      }
 
       return tmp;
 }