diff --git a/elab_lval.cc b/elab_lval.cc
index 51e674be9..c12250d6b 100644
--- a/elab_lval.cc
+++ b/elab_lval.cc
@@ -1132,6 +1132,12 @@ NetAssign_* PEIdent::elaborate_lval_net_class_member_(Design*des, NetScope*scope
 		    // part of the sig, as the l-value.
 		  NetNet*psig = class_type->find_static_property(method_name);
 		  ivl_assert(*this, psig);
+		  if (psig->get_const()) {
+			cerr << get_fileline() << ": error: Assignment to const signal `"
+			     << psig->name() << "` is not allowed." << endl;
+			des->errors++;
+			return nullptr;
+		  }
 
 		  lv = new NetAssign_(psig);
 		  return lv;
diff --git a/elab_sig.cc b/elab_sig.cc
index dfb2a44c2..f023e0dbb 100644
--- a/elab_sig.cc
+++ b/elab_sig.cc
@@ -419,6 +419,14 @@ void netclass_t::elaborate_sig(Design*des, PClass*pclass)
 	    auto sig = new NetNet(class_scope_, cur->first, NetNet::REG,
 				  use_type);
 	    sig->set_line(cur->second);
+	    sig->set_const(cur->second.qual.test_const());
+
+	    if (cur->second.qual.test_const() &&
+		cur->second.has_initializer) {
+		  int pidx = property_idx_from_name(cur->first);
+		  ivl_assert(cur->second, pidx >= 0);
+		  set_prop_initialized(pidx);
+	    }
       }
 
       for (map<perm_string,PFunction*>::iterator cur = pclass->funcs.begin()
diff --git a/pform_pclass.cc b/pform_pclass.cc
index e9276a49a..2e6694677 100644
--- a/pform_pclass.cc
+++ b/pform_pclass.cc
@@ -87,13 +87,14 @@ void pform_class_property(const struct vlltype&loc,
 	    }
 
 	    pform_cur_class->type->properties[curp->name.first]
-		  = class_type_t::prop_info_t(property_qual,use_type);
+		  = class_type_t::prop_info_t(property_qual, use_type,
+					    curp->expr != nullptr);
 	    FILE_NAME(&pform_cur_class->type->properties[curp->name.first], loc);
 
 	    if (PExpr*rval = curp->expr.release()) {
 		  PExpr*lval = new PEIdent(curp->name.first, curp->name.second);
 		  FILE_NAME(lval, loc);
-		  PAssign*tmp = new PAssign(lval, rval);
+		  auto tmp = new PAssign(lval, rval, false, true);
 		  FILE_NAME(tmp, loc);
 
 		  if (property_qual.test_static())
diff --git a/pform_types.h b/pform_types.h
index 021229e53..f0ff20ada 100644
--- a/pform_types.h
+++ b/pform_types.h
@@ -401,11 +401,14 @@ struct class_type_t : public data_type_t {
 	// This is a map of the properties. Map the name to the type.
       struct prop_info_t : public LineInfo {
 	    inline prop_info_t() : qual(property_qualifier_t::make_none()) { }
-	    inline prop_info_t(property_qualifier_t q, data_type_t*t) : qual(q), type(t) { }
+	    inline prop_info_t(property_qualifier_t q, data_type_t *t,
+			       bool init)
+	    : qual(q), type(t), has_initializer(init) { }
 	    prop_info_t(prop_info_t&&) = default;
 	    prop_info_t& operator=(prop_info_t&&) = default;
 	    property_qualifier_t qual;
 	    std::unique_ptr<data_type_t> type;
+	    bool has_initializer = false;
       };
       std::map<perm_string, struct prop_info_t> properties;