diff --git a/src/protocol/mod.rs b/src/protocol/mod.rs
index c7c4ba07d617734fe1aaab99fcbe75c5634f550b..1b22d31e02ca3dd2218e5327823727bb2a53e821 100644
--- a/src/protocol/mod.rs
+++ b/src/protocol/mod.rs
@@ -16,6 +16,8 @@ use crate::protocol::input_source::*;
 use crate::protocol::parser::*;
 use crate::protocol::type_table::*;
 
+pub use parser::type_table::TypeId;
+
 /// A protocol description module
 pub struct Module {
     pub(crate) source: InputSource,
@@ -106,7 +108,7 @@ impl ProtocolDescription {
         // - check number of arguments by retrieving the one instantiated
         //   monomorph
         let concrete_type = ConcreteType{ parts: vec![ConcreteTypePart::Component(definition_id, 0)] };
-        let mono_index = self.types.get_procedure_monomorph_index(&definition_id, &concrete_type.parts).unwrap();
+        let mono_index = self.types.get_procedure_monomorph_type_id(&definition_id, &concrete_type.parts).unwrap();
         let mono_type = self.types.get_procedure_monomorph(mono_index);
         if mono_type.arg_types.len() != arguments.values.len() {
             return Err(ComponentCreationError::InvalidNumArguments);