diff --git a/src/protocol/eval/executor.rs b/src/protocol/eval/executor.rs
index 670993cbc27ba8d66c0c91e19b18288c5e7742cf..8a80bd8dce90a3dc81de4d03d545a90e2b1a5d27 100644
--- a/src/protocol/eval/executor.rs
+++ b/src/protocol/eval/executor.rs
@@ -226,7 +226,6 @@ impl Prompt {
         };
 
         // Maybe do typechecking in the future?
-        debug_assert!((monomorph_idx as usize) < _types.get_base_definition(&def).unwrap().definition.procedure_monomorphs().len());
         let new_frame = Frame::new(heap, def, monomorph_idx);
         let max_stack_size = new_frame.max_stack_size;
         prompt.frames.push(new_frame);
@@ -475,7 +474,7 @@ impl Prompt {
                         },
                         Expression::Select(expr) => {
                             let subject= cur_frame.expr_values.pop_back().unwrap();
-                            let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                            let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                             let field_idx = mono_data.expr_data[expr.unique_id_in_definition as usize].field_or_monomorph_idx as u32;
 
                             // Note: same as above: clone if value lives on expr stack, simply
@@ -517,7 +516,7 @@ impl Prompt {
                                 }
                                 Literal::Integer(lit_value) => {
                                     use ConcreteTypePart as CTP;
-                                    let def_types = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                                    let def_types = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                                     let concrete_type = &def_types.expr_data[expr.unique_id_in_definition as usize].expr_type;
 
                                     debug_assert_eq!(concrete_type.parts.len(), 1);
@@ -559,7 +558,7 @@ impl Prompt {
                             cur_frame.expr_values.push_back(value);
                         },
                         Expression::Cast(expr) => {
-                            let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                            let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                             let output_type = &mono_data.expr_data[expr.unique_id_in_definition as usize].expr_type;
 
                             // Typechecking reduced this to two cases: either we
@@ -741,7 +740,7 @@ impl Prompt {
                                     }
 
                                     // Determine the monomorph index of the function we're calling
-                                    let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                                    let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                                     let call_data = &mono_data.expr_data[expr.unique_id_in_definition as usize];
 
                                     // Push the new frame and reserve its stack size
@@ -974,7 +973,7 @@ impl Prompt {
                     "mismatch in expr stack size and number of arguments for new statement"
                 );
 
-                let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                 let expr_data = &mono_data.expr_data[call_expr.unique_id_in_definition as usize];
 
                 // Note that due to expression value evaluation they exist in