diff --git a/src/main.rs b/src/main.rs
index 5ddb94e..852d1ad 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -204,8 +204,8 @@ impl LdmcMorphism {
     pub fn generate_call(&self, dict: &mut impl TypeDict, σ: &std::collections::HashMap<laddertypes::TypeID, laddertypes::TypeTerm>, i: u64) {
         match self {
             LdmcMorphism::Primitive(prim_morph) => {
-                let src_c_type = get_c_repr_type(dict, prim_morph.src_type.clone(), true).expect("cant get c-repr type for src type");
-                let dst_c_type = get_c_repr_type(dict, prim_morph.dst_type.clone(), true).expect("cant get c-repr type for dst type");
+                let src_c_type = get_c_repr_type(dict, prim_morph.src_type.clone().apply_substitution(&|k| σ.get(k).cloned()).clone(), true).expect("cant get c-repr type for src type");
+                let dst_c_type = get_c_repr_type(dict, prim_morph.dst_type.clone().apply_substitution(&|k| σ.get(k).cloned()).clone(), true).expect("cant get c-repr type for dst type");
 
                 let src_buf = if i%2 == 0 { "bufA" } else { "bufB" };
                 let dst_buf = if i%2 == 0 { "bufB" } else { "bufA" };
@@ -223,8 +223,8 @@ impl LdmcMorphism {
                     '}');
             }
             LdmcMorphism::LengthPrefixMap { length_prefix_type, item_morph } => {
-                let src_c_type = get_c_repr_type(dict, self.get_type().src_type, true).expect("cant get c-repr type for src type");
-                let dst_c_type = get_c_repr_type(dict, self.get_type().dst_type, true).expect("cant get c-repr type for dst type");
+                let src_c_type = get_c_repr_type(dict, self.get_type().src_type.clone().apply_substitution(&|k| σ.get(k).cloned()).clone(), true).expect("cant get c-repr type for src type");
+                let dst_c_type = get_c_repr_type(dict, self.get_type().dst_type.clone().apply_substitution(&|k| σ.get(k).cloned()).clone(), true).expect("cant get c-repr type for dst type");
 
                 let map_fn = match (src_c_type.as_str(), dst_c_type.as_str()) {
                     ("struct LengthPrefixUInt64Array", "struct LengthPrefixUInt64Array") => "length_prefix_array_map_64_to_64",