diff --git a/vhdlpp/entity.cc b/vhdlpp/entity.cc
index ffb562fe6..d4d6308db 100644
--- a/vhdlpp/entity.cc
+++ b/vhdlpp/entity.cc
@@ -56,7 +56,8 @@ static void dump_design_entity(ostream&out, Entity*obj)
 		       ; cur != obj->ports.end() ; ++cur) {
 		  InterfacePort*item = *cur;
 		  out << setw(6) << "" << item->name
-		      << " : " << item->mode << endl;
+		      << " : " << item->mode
+		      << ", type=" << item->type_name << endl;
 	    }
       }
 }
diff --git a/vhdlpp/entity.h b/vhdlpp/entity.h
index 46e78e33c..03a62aa1b 100644
--- a/vhdlpp/entity.h
+++ b/vhdlpp/entity.h
@@ -27,8 +27,12 @@ typedef enum { PORT_NONE=0, PORT_IN, PORT_OUT } port_mode_t;
 
 class InterfacePort {
     public:
+	// Port direction from the source code.
       port_mode_t mode;
+	// Name of the port from the source code
       perm_string name;
+	// Name of interface type as given in the source code.
+      perm_string type_name;
 };
 
 class Entity {
diff --git a/vhdlpp/entity_elaborate.cc b/vhdlpp/entity_elaborate.cc
index 8f4fa7d76..699cc732d 100644
--- a/vhdlpp/entity_elaborate.cc
+++ b/vhdlpp/entity_elaborate.cc
@@ -54,6 +54,16 @@ int Entity::elaborate()
 		       ; cur != ports.end() ; ++cur) {
 		  InterfacePort*port = *cur;
 
+		    // FIXME: this is a stub. This port handling code
+		    // currently only supports std_logic signal tyes,
+		    // so just assert that the user asked for std_logic.
+		  if (port->type_name != "std_logic") {
+			cerr << "sorry: VHDL only supports std_logic ports."
+			     << " Expecting std_logic, but got \""
+			     << port->type_name << "\"" << endl;
+			errors += 1;
+		  }
+
 		  if (sep) cout << sep;
 		  else sep = ", ";
 
diff --git a/vhdlpp/parse.y b/vhdlpp/parse.y
index 39296be0f..26335ccfd 100644
--- a/vhdlpp/parse.y
+++ b/vhdlpp/parse.y
@@ -172,6 +172,7 @@ interface_element
       { InterfacePort*tmp = new InterfacePort;
 	tmp->mode = $3;
 	tmp->name = lex_strings.make($1);
+	tmp->type_name = lex_strings.make($4);
 	delete[]$1;
 	delete[]$4;
 	$$ = tmp;
@@ -180,7 +181,7 @@ interface_element
 
 interface_list
   : interface_list ';' interface_element
-      { std:list<InterfacePort*>*tmp = $1;
+      { std::list<InterfacePort*>*tmp = $1;
 	tmp->push_back($3);
 	$$ = tmp;
       }