diff --git a/Module.h b/Module.h
index 48c83af88..993a8c0df 100644
--- a/Module.h
+++ b/Module.h
@@ -97,7 +97,7 @@ class Module : public PScopeExtra, public PNamedItem {
 	/* specparams are simpler than other parameters, in that they
 	   can have a range, but not an explicit type. The restrictions
 	   are enforced by the parser. */
-      map<perm_string,param_expr_t>specparams;
+      map<perm_string,param_expr_t*>specparams;
 
 	/* The module also has defparam assignments which don't create
 	   new parameters within the module, but may be used to set
diff --git a/PScope.h b/PScope.h
index 1c0760ad5..aa0eddf84 100644
--- a/PScope.h
+++ b/PScope.h
@@ -105,8 +105,8 @@ class LexicalScope {
 
 	    SymbolType symbol_type() const;
       };
-      map<perm_string,param_expr_t>parameters;
-      map<perm_string,param_expr_t>localparams;
+      map<perm_string,param_expr_t*>parameters;
+      map<perm_string,param_expr_t*>localparams;
 
 	// Defined types in the scope.
       map<perm_string,data_type_t*>typedefs;
diff --git a/elab_scope.cc b/elab_scope.cc
index 4afd4b680..5554a0768 100644
--- a/elab_scope.cc
+++ b/elab_scope.cc
@@ -63,7 +63,7 @@ void set_scope_timescale(Design*des, NetScope*scope, PScope*pscope)
       des->set_precision(pscope->time_precision);
 }
 
-typedef map<perm_string,LexicalScope::param_expr_t>::const_iterator mparm_it_t;
+typedef map<perm_string,LexicalScope::param_expr_t*>::const_iterator mparm_it_t;
 
 static void collect_parm_item_(Design*des, NetScope*scope, perm_string name,
 			       const LexicalScope::param_expr_t&cur,
@@ -110,59 +110,59 @@ static void collect_parm_item_(Design*des, NetScope*scope, perm_string name,
 }
 
 static void collect_scope_parameters_(Design*des, NetScope*scope,
-      const map<perm_string,LexicalScope::param_expr_t>&parameters)
+      const map<perm_string,LexicalScope::param_expr_t*>&parameters)
 {
       for (mparm_it_t cur = parameters.begin()
 		 ; cur != parameters.end() ;  ++ cur ) {
 
 	      // A parameter can not have the same name as a genvar.
 	    if (scope->find_genvar((*cur).first)) {
-		  cerr << cur->second.get_fileline()
+		  cerr << cur->second->get_fileline()
 		       << ": error: parameter and genvar in '"
 		       << scope->fullname() << "' have the same name '"
 		       << (*cur).first << "'." << endl;
 		  des->errors += 1;
 	    }
 
-	    collect_parm_item_(des, scope, (*cur).first, (*cur).second, false, false);
+	    collect_parm_item_(des, scope, cur->first, *(cur->second), false, false);
       }
 }
 
 static void collect_scope_localparams_(Design*des, NetScope*scope,
-      const map<perm_string,LexicalScope::param_expr_t>&localparams)
+      const map<perm_string,LexicalScope::param_expr_t*>&localparams)
 {
       for (mparm_it_t cur = localparams.begin()
 		 ; cur != localparams.end() ;  ++ cur ) {
 
 	      // A localparam can not have the same name as a genvar.
 	    if (scope->find_genvar((*cur).first)) {
-		  cerr << cur->second.get_fileline()
+		  cerr << cur->second->get_fileline()
 		       << ": error: localparam and genvar in '"
 		       << scope->fullname() << "' have the same name '"
 		       << (*cur).first << "'." << endl;
 		  des->errors += 1;
 	    }
 
-	    collect_parm_item_(des, scope, (*cur).first, (*cur).second, false, true);
+	    collect_parm_item_(des, scope, cur->first, *(cur->second), false, true);
       }
 }
 
 static void collect_scope_specparams_(Design*des, NetScope*scope,
-      const map<perm_string,LexicalScope::param_expr_t>&specparams)
+      const map<perm_string,LexicalScope::param_expr_t*>&specparams)
 {
       for (mparm_it_t cur = specparams.begin()
 		 ; cur != specparams.end() ;  ++ cur ) {
 
 	      // A specparam can not have the same name as a genvar.
 	    if (scope->find_genvar((*cur).first)) {
-		  cerr << cur->second.get_fileline()
+		  cerr << cur->second->get_fileline()
 		       << ": error: specparam and genvar in '"
 		       << scope->fullname() << "' have the same name '"
 		       << (*cur).first << "'." << endl;
 		  des->errors += 1;
 	    }
 
-	    collect_parm_item_(des, scope, (*cur).first, (*cur).second, true, false);
+	    collect_parm_item_(des, scope, cur->first, *(cur->second), true, false);
       }
 }
 
diff --git a/pform.cc b/pform.cc
index d6b41f3d3..c0a57ffcc 100644
--- a/pform.cc
+++ b/pform.cc
@@ -3059,27 +3059,28 @@ void pform_set_parameter(const struct vlltype&loc,
       }
 
       assert(expr);
-      Module::param_expr_t&parm = scope->parameters[name];
-      FILE_NAME(&parm, loc);
+      Module::param_expr_t*parm = new Module::param_expr_t();
+      FILE_NAME(parm, loc);
 
-      parm.expr = expr;
+      add_local_symbol(scope, name, parm);
+      scope->parameters[name] = parm;
 
-      parm.type = type;
+      parm->expr = expr;
+
+      parm->type = type;
       if (range) {
 	    assert(range->size() == 1);
 	    pform_range_t&rng = range->front();
 	    assert(rng.first);
 	    assert(rng.second);
-	    parm.msb = rng.first;
-	    parm.lsb = rng.second;
+	    parm->msb = rng.first;
+	    parm->lsb = rng.second;
       } else {
-	    parm.msb = 0;
-	    parm.lsb = 0;
+	    parm->msb = 0;
+	    parm->lsb = 0;
       }
-      parm.signed_flag = signed_flag;
-      parm.range = value_range;
-
-      add_local_symbol(scope, name, &parm);
+      parm->signed_flag = signed_flag;
+      parm->range = value_range;
 
 	// Only a Module keeps the position of the parameter.
       if ((dynamic_cast<Module*>(scope)) && (scope == pform_cur_module.front()))
@@ -3097,27 +3098,28 @@ void pform_set_localparam(const struct vlltype&loc,
       }
 
       assert(expr);
-      Module::param_expr_t&parm = scope->localparams[name];
-      FILE_NAME(&parm, loc);
+      Module::param_expr_t*parm = new Module::param_expr_t();
+      FILE_NAME(parm, loc);
 
-      parm.expr = expr;
+      add_local_symbol(scope, name, parm);
+      scope->localparams[name] = parm;
 
-      parm.type = type;
+      parm->expr = expr;
+
+      parm->type = type;
       if (range) {
 	    assert(range->size() == 1);
 	    pform_range_t&rng = range->front();
 	    assert(rng.first);
 	    assert(rng.second);
-	    parm.msb = rng.first;
-	    parm.lsb = rng.second;
+	    parm->msb = rng.first;
+	    parm->lsb = rng.second;
       } else {
-	    parm.msb  = 0;
-	    parm.lsb  = 0;
+	    parm->msb  = 0;
+	    parm->lsb  = 0;
       }
-      parm.signed_flag = signed_flag;
-      parm.range = 0;
-
-      add_local_symbol(scope, name, &parm);
+      parm->signed_flag = signed_flag;
+      parm->range = 0;
 }
 
 void pform_set_specparam(const struct vlltype&loc, perm_string name,
@@ -3128,28 +3130,29 @@ void pform_set_specparam(const struct vlltype&loc, perm_string name,
       assert(scope == lexical_scope);
 
       assert(expr);
-      Module::param_expr_t&parm = pform_cur_module.front()->specparams[name];
-      FILE_NAME(&parm, loc);
+      Module::param_expr_t*parm = new Module::param_expr_t();
+      FILE_NAME(parm, loc);
 
-      parm.expr = expr;
+      add_local_symbol(scope, name, parm);
+      pform_cur_module.front()->specparams[name] = parm;
+
+      parm->expr = expr;
 
       if (range) {
 	    assert(range->size() == 1);
 	    pform_range_t&rng = range->front();
 	    assert(rng.first);
 	    assert(rng.second);
-	    parm.type = IVL_VT_LOGIC;
-	    parm.msb = rng.first;
-	    parm.lsb = rng.second;
+	    parm->type = IVL_VT_LOGIC;
+	    parm->msb = rng.first;
+	    parm->lsb = rng.second;
       } else {
-	    parm.type = IVL_VT_NO_TYPE;
-	    parm.msb  = 0;
-	    parm.lsb  = 0;
+	    parm->type = IVL_VT_NO_TYPE;
+	    parm->msb  = 0;
+	    parm->lsb  = 0;
       }
-      parm.signed_flag = false;
-      parm.range = 0;
-
-      add_local_symbol(scope, name, &parm);
+      parm->signed_flag = false;
+      parm->range = 0;
 }
 
 void pform_set_defparam(const pform_name_t&name, PExpr*expr)
diff --git a/pform_dump.cc b/pform_dump.cc
index 26a079786..97a6f13af 100644
--- a/pform_dump.cc
+++ b/pform_dump.cc
@@ -1359,22 +1359,22 @@ void LexicalScope::dump_typedefs_(ostream&out, unsigned indent) const
 
 void LexicalScope::dump_parameters_(ostream&out, unsigned indent) const
 {
-      typedef map<perm_string,param_expr_t>::const_iterator parm_iter_t;
+      typedef map<perm_string,param_expr_t*>::const_iterator parm_iter_t;
       for (parm_iter_t cur = parameters.begin()
 		 ; cur != parameters.end() ; ++ cur ) {
 	    out << setw(indent) << "" << "parameter "
-                << (*cur).second.type << " ";
-	    if ((*cur).second.signed_flag)
+                << (*cur).second->type << " ";
+	    if ((*cur).second->signed_flag)
 		  out << "signed ";
-	    if ((*cur).second.msb)
-		  out << "[" << *(*cur).second.msb << ":"
-		      << *(*cur).second.lsb << "] ";
+	    if ((*cur).second->msb)
+		  out << "[" << *(*cur).second->msb << ":"
+		      << *(*cur).second->lsb << "] ";
 	    out << (*cur).first << " = ";
-	    if ((*cur).second.expr)
-		  out << *(*cur).second.expr;
+	    if ((*cur).second->expr)
+		  out << *(*cur).second->expr;
 	    else
 		  out << "/* ERROR */";
-	    for (LexicalScope::range_t*tmp = (*cur).second.range
+	    for (LexicalScope::range_t*tmp = (*cur).second->range
 		       ; tmp ; tmp = tmp->next) {
 		  if (tmp->exclude_flag)
 			out << " exclude ";
@@ -1408,16 +1408,16 @@ void LexicalScope::dump_parameters_(ostream&out, unsigned indent) const
 
 void LexicalScope::dump_localparams_(ostream&out, unsigned indent) const
 {
-      typedef map<perm_string,param_expr_t>::const_iterator parm_iter_t;
+      typedef map<perm_string,param_expr_t*>::const_iterator parm_iter_t;
       for (parm_iter_t cur = localparams.begin()
 		 ; cur != localparams.end() ; ++ cur ) {
 	    out << setw(indent) << "" << "localparam ";
-	    if ((*cur).second.msb)
-		  out << "[" << *(*cur).second.msb << ":"
-		      << *(*cur).second.lsb << "] ";
+	    if ((*cur).second->msb)
+		  out << "[" << *(*cur).second->msb << ":"
+		      << *(*cur).second->lsb << "] ";
 	    out << (*cur).first << " = ";
-	    if ((*cur).second.expr)
-		  out << *(*cur).second.expr << ";" << endl;
+	    if ((*cur).second->expr)
+		  out << *(*cur).second->expr << ";" << endl;
 	    else
 		  out << "/* ERROR */;" << endl;
       }
@@ -1513,16 +1513,16 @@ void PClass::dump(ostream&out, unsigned indent) const
 
 void Module::dump_specparams_(ostream&out, unsigned indent) const
 {
-      typedef map<perm_string,param_expr_t>::const_iterator parm_iter_t;
+      typedef map<perm_string,param_expr_t*>::const_iterator parm_iter_t;
       for (parm_iter_t cur = specparams.begin()
 		 ; cur != specparams.end() ; ++ cur ) {
 	    out << setw(indent) << "" << "specparam ";
-	    if ((*cur).second.msb)
-		  out << "[" << *(*cur).second.msb << ":"
-		      << *(*cur).second.lsb << "] ";
+	    if ((*cur).second->msb)
+		  out << "[" << *(*cur).second->msb << ":"
+		      << *(*cur).second->lsb << "] ";
 	    out << (*cur).first << " = ";
-	    if ((*cur).second.expr)
-		  out << *(*cur).second.expr << ";" << endl;
+	    if ((*cur).second->expr)
+		  out << *(*cur).second->expr << ";" << endl;
 	    else
 		  out << "/* ERROR */;" << endl;
       }