diff --git a/elab_scope.cc b/elab_scope.cc
index 9796ce7fc..53ebf37af 100644
--- a/elab_scope.cc
+++ b/elab_scope.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2016 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2000-2017 Stephen Williams (steve@icarus.com)
  * Copyright CERN 2013 / Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
@@ -509,8 +509,10 @@ static void elaborate_scope_class(Design*des, NetScope*scope, PClass*pclass)
 
       netclass_t*use_base_class = 0;
       if (base_class) {
-	    ivl_assert(*pclass, scope);
-	    use_base_class = scope->find_class(base_class->name);
+	    if (scope)
+		  use_base_class = scope->find_class(base_class->name);
+	    if (use_base_class == 0)
+		  use_base_class = des->find_class(base_class->name);
 	    if (use_base_class == 0) {
 		  cerr << pclass->get_fileline() << ": error: "
 		       << "Base class " << base_class->name
@@ -605,13 +607,9 @@ static void elaborate_scope_classes(Design*des, NetScope*scope,
 
 void elaborate_rootscope_classes(Design*des)
 {
-      if (pform_classes.empty())
-	    return;
-
-      for (map<perm_string,PClass*>::iterator cur = pform_classes.begin()
-		 ; cur != pform_classes.end() ; ++ cur) {
-	    blend_class_constructors(cur->second);
-	    elaborate_scope_class(des, 0, cur->second);
+      for (size_t idx = 0 ; idx < pform_classes.size() ; idx += 1) {
+            blend_class_constructors(pform_classes[idx]);
+            elaborate_scope_class(des, 0, pform_classes[idx]);
       }
 }
 
diff --git a/main.cc b/main.cc
index e814b7466..e80ba1983 100644
--- a/main.cc
+++ b/main.cc
@@ -1,5 +1,5 @@
 const char COPYRIGHT[] =
-          "Copyright (c) 1998-2016 Stephen Williams (steve@icarus.com)";
+          "Copyright (c) 1998-2017 Stephen Williams (steve@icarus.com)";
 
 /*
  *    This source code is free software; you can redistribute it
@@ -1056,9 +1056,8 @@ int main(int argc, char*argv[])
 		  pform_dump(out, cur->second);
 	    }
 	    out << "PFORM DUMP $ROOT CLASSES:" << endl;
-	    for (map<perm_string,PClass*>::iterator cur = pform_classes.begin()
-		       ; cur != pform_classes.end() ; ++ cur) {
-		  pform_dump(out, cur->second);
+	    for (size_t idx = 0 ; idx < pform_classes.size() ; idx += 1) {
+		  pform_dump(out, pform_classes[idx]);
 	    }
 	    out << "PFORM DUMP PACKAGES:" << endl;
 	    for (map<perm_string,PPackage*>::iterator pac = pform_packages.begin()
diff --git a/parse_api.h b/parse_api.h
index a698c3bee..87ae28d11 100644
--- a/parse_api.h
+++ b/parse_api.h
@@ -1,7 +1,7 @@
 #ifndef IVL_parse_api_H
 #define IVL_parse_api_H
 /*
- * Copyright (c) 2001-2014 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2001-2017 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -45,7 +45,7 @@ extern std::map<perm_string,PUdp*>   pform_primitives;
 extern std::map<perm_string,data_type_t*> pform_typedefs;
 extern std::set<enum_type_t*> pform_enum_sets;
 extern std::map<perm_string,PTaskFunc*> pform_tasks;
-extern std::map<perm_string,PClass*> pform_classes;
+extern std::vector<PClass*> pform_classes;
 extern std::map<perm_string,PPackage*> pform_packages;
 
 extern void pform_dump(std::ostream&out, const PClass*pac);
diff --git a/pform.cc b/pform.cc
index b9e36042e..0478fba79 100644
--- a/pform.cc
+++ b/pform.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998-2016 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1998-2017 Stephen Williams (steve@icarus.com)
  * Copyright CERN 2013 / Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
@@ -71,7 +71,7 @@ set<enum_type_t*>pform_enum_sets;
 /*
  * Class definitions in the $root scope go here.
  */
-map<perm_string,PClass*> pform_classes;
+vector<PClass*> pform_classes;
 
 /*
  * Task and function definitions in the $root scope go here.
@@ -467,7 +467,7 @@ PClass* pform_push_class_scope(const struct vlltype&loc, perm_string name,
 	/* If no scope was found then this is being defined in the
 	 * compilation unit scope. */
       if (scopex == 0) {
-	    pform_classes[name] = class_scope;
+	    pform_classes.push_back(class_scope);
 	    lexical_scope = class_scope;
 	    return class_scope;
       }