diff --git a/PExpr.cc b/PExpr.cc
index e60a3fbba..842bdc311 100644
--- a/PExpr.cc
+++ b/PExpr.cc
@@ -390,7 +390,7 @@ PEIdent::~PEIdent()
 
 static bool find_enum_constant(LexicalScope*scope, perm_string name)
 {
-      for (set<enum_type_t*,netenum_t*>::const_iterator cur = scope->enum_sets.begin() ;
+      for (vector<enum_type_t*>::const_iterator cur = scope->enum_sets.begin() ;
            cur != scope->enum_sets.end() ; ++ cur) {
 	    for (list<named_pexpr_t>::const_iterator idx = (*cur)->names->begin() ;
                  idx != (*cur)->names->end() ; ++ idx) {
diff --git a/PScope.h b/PScope.h
index e500a7e02..fd573350e 100644
--- a/PScope.h
+++ b/PScope.h
@@ -139,7 +139,7 @@ class LexicalScope {
       std::list<PCallTask*> elab_tasks;
 
 	// Enumeration sets.
-      std::set<enum_type_t*> enum_sets;
+      std::vector<enum_type_t*> enum_sets;
 
         // A count of the generate constructs in this scope. This is
         // used to automatically name unnamed generate blocks, as
diff --git a/elab_scope.cc b/elab_scope.cc
index b145bb887..244e1bed1 100644
--- a/elab_scope.cc
+++ b/elab_scope.cc
@@ -393,7 +393,7 @@ static void elaborate_scope_enumeration(Design*des, NetScope*scope,
 }
 
 static void elaborate_scope_enumerations(Design*des, NetScope*scope,
-					 const set<enum_type_t*>&enum_types)
+					 const vector<enum_type_t*>&enum_types)
 {
       if (debug_scopes) {
 	    cerr << scope->get_fileline() << ": " << __func__ << ": "
@@ -402,7 +402,7 @@ static void elaborate_scope_enumerations(Design*des, NetScope*scope,
 		 << endl;
       }
 
-      for (set<enum_type_t*>::const_iterator cur = enum_types.begin()
+      for (vector<enum_type_t*>::const_iterator cur = enum_types.begin()
 		 ; cur != enum_types.end() ; ++ cur) {
 	    enum_type_t*curp = *cur;
 	    elaborate_scope_enumeration(des, scope, curp);
diff --git a/pform.cc b/pform.cc
index 1ee8de7d9..3abce4071 100644
--- a/pform.cc
+++ b/pform.cc
@@ -829,8 +829,10 @@ static void pform_put_wire_in_scope(perm_string name, PWire*net)
 
 void pform_put_enum_type_in_scope(enum_type_t*enum_set)
 {
-      if (lexical_scope->enum_sets.count(enum_set))
-            return;
+      if (std::find(lexical_scope->enum_sets.begin(),
+		    lexical_scope->enum_sets.end(), enum_set) !=
+          lexical_scope->enum_sets.end())
+	    return;
 
       set<perm_string> enum_names;
       list<named_pexpr_t>::const_iterator cur;
@@ -846,7 +848,7 @@ void pform_put_enum_type_in_scope(enum_type_t*enum_set)
 	    }
       }
 
-      lexical_scope->enum_sets.insert(enum_set);
+      lexical_scope->enum_sets.push_back(enum_set);
 }
 
 PWire*pform_get_make_wire_in_scope(const struct vlltype&, perm_string name,
diff --git a/pform_dump.cc b/pform_dump.cc
index b563e9041..32c4fb9d8 100644
--- a/pform_dump.cc
+++ b/pform_dump.cc
@@ -1544,7 +1544,7 @@ void LexicalScope::dump_localparams_(ostream&out, unsigned indent) const
 
 void LexicalScope::dump_enumerations_(ostream&out, unsigned indent) const
 {
-      for (set<enum_type_t*>::const_iterator cur = enum_sets.begin()
+      for (vector<enum_type_t*>::const_iterator cur = enum_sets.begin()
 		 ; cur != enum_sets.end() ; ++ cur) {
 	    out << setw(indent) << "" << "enum {" << endl;