diff --git a/src/hw-cbmc/hw_cbmc_parse_options.cpp b/src/hw-cbmc/hw_cbmc_parse_options.cpp
index 55690fafa..3f1c9102d 100644
--- a/src/hw-cbmc/hw_cbmc_parse_options.cpp
+++ b/src/hw-cbmc/hw_cbmc_parse_options.cpp
@@ -86,17 +86,16 @@ int hw_cbmc_parse_optionst::doit()
   prop_convt &prop_conv=cbmc_solver->prop_conv();
   hw_bmct hw_bmc(options, symbol_table, ui_message_handler, prop_conv);
 
-  if(cmdline.isset("bound"))
-    hw_bmc.unwind_no_timeframes=safe_string2unsigned(cmdline.get_value("bound"))+1;
-  else
-    hw_bmc.unwind_no_timeframes=1;
-
   goto_functionst goto_functions;
 
-  int get_goto_program_ret=get_goto_program(options, hw_bmc, goto_functions);
+  int get_goto_program_ret=get_goto_program(
+    options, hw_bmc.bmc_constraints, goto_functions);
   if(get_goto_program_ret!=-1)
     return get_goto_program_ret;
 
+  hw_bmc.unwind_no_timeframes=get_bound();
+  hw_bmc.unwind_module=get_top_module();
+
   label_properties(goto_functions);
 
   if(cmdline.isset("show-properties"))
@@ -115,7 +114,7 @@ int hw_cbmc_parse_optionst::doit()
 
 /*******************************************************************\
 
-Function: hw_cbmc_parse_optionst::get_modules
+Function: hw_cbmc_parse_optionst::get_top_module
 
   Inputs:
 
@@ -125,12 +124,8 @@ Function: hw_cbmc_parse_optionst::get_modules
 
 \*******************************************************************/
 
-int hw_cbmc_parse_optionst::get_modules(bmct &bmc)
+irep_idt hw_cbmc_parse_optionst::get_top_module()
 {
-  //
-  // unwinding of transition systems
-  //
-
   std::string top_module;
 
   if(cmdline.isset("module"))
@@ -138,15 +133,62 @@ int hw_cbmc_parse_optionst::get_modules(bmct &bmc)
   else if(cmdline.isset("top"))
     top_module=cmdline.get_value("top");
 
-  if(top_module!="")
+  if(top_module=="")
+    return irep_idt();
+
+  return get_module(
+    symbol_table, top_module, get_message_handler()).name;
+}
+
+/*******************************************************************\
+
+Function: hw_cbmc_parse_optionst::get_bound
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: add additional (synchonous) modules
+
+\*******************************************************************/
+
+unsigned hw_cbmc_parse_optionst::get_bound()
+{
+  if(cmdline.isset("bound"))
+    return safe_string2unsigned(cmdline.get_value("bound"))+1;
+  else
+    return 1;
+}
+
+/*******************************************************************\
+
+Function: hw_cbmc_parse_optionst::get_modules
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: add additional (synchonous) modules
+
+\*******************************************************************/
+
+int hw_cbmc_parse_optionst::get_modules(expr_listt &bmc_constraints)
+{
+  //
+  // unwinding of transition systems
+  //
+
+  irep_idt top_module=get_top_module();
+
+  if(!top_module.empty())
   {
     try
     {
-      const symbolt &symbol=
-        get_module(symbol_table, top_module, get_message_handler());
-
       if(cmdline.isset("gen-interface"))
       {
+        const symbolt &symbol=
+          namespacet(symbol_table).lookup(top_module);
+
         if(cmdline.isset("outfile"))
         {
           std::ofstream out(cmdline.get_value("outfile").c_str());
@@ -164,10 +206,6 @@ int hw_cbmc_parse_optionst::get_modules(bmct &bmc)
         return 0; // done
       }
       
-      hw_bmct &hw_bmc=dynamic_cast<hw_bmct &>(bmc);
-
-      hw_bmc.unwind_module=symbol.name;
-
       //
       // map HDL variables to C variables
       //
@@ -176,10 +214,10 @@ int hw_cbmc_parse_optionst::get_modules(bmct &bmc)
 
       map_vars(
         symbol_table,
-        symbol.name,
-        hw_bmc.bmc_constraints,
-        ui_message_handler,
-        hw_bmc.unwind_no_timeframes);
+        top_module,
+        bmc_constraints,
+        get_message_handler(),
+        get_bound());
     }
 
     catch(int e) { return 6; }
diff --git a/src/hw-cbmc/hw_cbmc_parse_options.h b/src/hw-cbmc/hw_cbmc_parse_options.h
index fbf814e20..b7d2aaf1d 100644
--- a/src/hw-cbmc/hw_cbmc_parse_options.h
+++ b/src/hw-cbmc/hw_cbmc_parse_options.h
@@ -27,7 +27,10 @@ class hw_cbmc_parse_optionst:public cbmc_parse_optionst
   }
   
 protected:
-  virtual int get_modules(bmct &bmc);
+  virtual int get_modules(expr_listt &bmc_constraints);
+
+  irep_idt get_top_module();
+  unsigned get_bound();
 };
 
 #endif