diff --git a/passes/opt/opt_clean.cc b/passes/opt/opt_clean.cc
index aabdbf013..c5b25816c 100644
--- a/passes/opt/opt_clean.cc
+++ b/passes/opt/opt_clean.cc
@@ -347,16 +347,16 @@ struct OptCleanPass : public Pass {
 		ct_reg.setup_internals_mem();
 		ct_reg.setup_stdcells_mem();
 
-		for (auto &mod_it : design->modules_) {
-			if (!design->selected_whole_module(mod_it.first)) {
-				if (design->selected(mod_it.second))
-					log("Skipping module %s as it is only partially selected.\n", id2cstr(mod_it.second->name));
+		for (auto mod : design->modules()) {
+			if (!design->selected_whole_module(mod->name)) {
+				if (design->selected(mod))
+					log("Skipping module %s as it is only partially selected.\n", id2cstr(mod->name));
 				continue;
 			}
-			if (mod_it.second->processes.size() > 0) {
-				log("Skipping module %s as it contains processes.\n", mod_it.second->name.c_str());
+			if (!mod->processes.empty()) {
+				log("Skipping module %s as it contains processes.\n", mod->name.c_str());
 			} else {
-				rmunused_module(mod_it.second, purge_mode, true);
+				rmunused_module(mod, purge_mode, true);
 			}
 		}
 
@@ -411,11 +411,11 @@ struct CleanPass : public Pass {
 		count_rm_cells = 0;
 		count_rm_wires = 0;
 
-		for (auto &mod_it : design->modules_) {
-			if (design->selected_whole_module(mod_it.first) && mod_it.second->processes.size() == 0)
+		for (auto mod : design->modules()) {
+			if (design->selected_whole_module(mod->name) && mod->processes.empty())
 				do {
 					design->scratchpad_unset("opt.did_something");
-					rmunused_module(mod_it.second, purge_mode, false);
+					rmunused_module(mod, purge_mode, false);
 				} while (design->scratchpad_get_bool("opt.did_something"));
 		}