diff --git a/compiler/builtins/src/std.rs b/compiler/builtins/src/std.rs
index 05b17057e4..fe5d2afdd1 100644
--- a/compiler/builtins/src/std.rs
+++ b/compiler/builtins/src/std.rs
@@ -144,12 +144,10 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
     );
 
     // sub or (-) : Num a, Num a -> Num a
-    add_type!(
+    add_top_level_function_type!(
         Symbol::NUM_SUB,
-        top_level_function(
-            vec![num_type(flex(TVAR1)), num_type(flex(TVAR1))],
-            Box::new(num_type(flex(TVAR1))),
-        ),
+        vec![num_type(flex(TVAR1)), num_type(flex(TVAR1))],
+        Box::new(num_type(flex(TVAR1))),
     );
 
     // subWrap : Int range, Int range -> Int range
@@ -391,12 +389,10 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
     );
 
     // mod : Int a, Int a -> Result (Int a) [ DivByZero ]*
-    add_type!(
+    add_top_level_function_type!(
         Symbol::NUM_MOD_INT,
-        top_level_function(
-            vec![int_type(flex(TVAR1)), int_type(flex(TVAR1))],
-            Box::new(result_type(int_type(flex(TVAR1)), div_by_zero.clone())),
-        ),
+        vec![int_type(flex(TVAR1)), int_type(flex(TVAR1))],
+        Box::new(result_type(int_type(flex(TVAR1)), div_by_zero.clone())),
     );
 
     // isMultipleOf : Int a, Int a -> Bool
@@ -850,9 +846,11 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
     });
 
     // keepErrs: List before, (before -> Result * after) -> List after
-    add_type!(Symbol::LIST_KEEP_ERRS, {
+    {
         let_tvars! { star, cvar, before, after};
-        top_level_function(
+
+        add_top_level_function_type!(
+            Symbol::LIST_KEEP_ERRS,
             vec![
                 list_type(flex(before)),
                 closure(
@@ -863,7 +861,7 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
             ],
             Box::new(list_type(flex(after))),
         )
-    });
+    };
 
     // range : Int a, Int a -> List (Int a)
     add_type!(Symbol::LIST_RANGE, {
@@ -910,11 +908,12 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
         )
     });
 
-    // map3 : List a, List b, List c, (a, b, c -> d) -> List d
-    add_type!(Symbol::LIST_MAP3, {
+    {
         let_tvars! {a, b, c, d, cvar};
 
-        top_level_function(
+        // map3 : List a, List b, List c, (a, b, c -> d) -> List d
+        add_top_level_function_type!(
+            Symbol::LIST_MAP3,
             vec![
                 list_type(flex(a)),
                 list_type(flex(b)),
@@ -923,7 +922,7 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
             ],
             Box::new(list_type(flex(d))),
         )
-    });
+    };
 
     // append : List elem, elem -> List elem
     add_type!(
@@ -1263,15 +1262,13 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
     );
 
     // mapErr : Result a x, (x -> y) -> Result a x
-    add_type!(
+    add_top_level_function_type!(
         Symbol::RESULT_MAP_ERR,
-        top_level_function(
-            vec![
-                result_type(flex(TVAR1), flex(TVAR3)),
-                closure(vec![flex(TVAR3)], TVAR4, Box::new(flex(TVAR2))),
-            ],
-            Box::new(result_type(flex(TVAR1), flex(TVAR2))),
-        ),
+        vec![
+            result_type(flex(TVAR1), flex(TVAR3)),
+            closure(vec![flex(TVAR3)], TVAR4, Box::new(flex(TVAR2))),
+        ],
+        Box::new(result_type(flex(TVAR1), flex(TVAR2))),
     );
 
     // after : Result a err, (a -> Result b err) -> Result b err
diff --git a/compiler/gen/src/llvm/build.rs b/compiler/gen/src/llvm/build.rs
index 776b168f0b..455bb7c87e 100644
--- a/compiler/gen/src/llvm/build.rs
+++ b/compiler/gen/src/llvm/build.rs
@@ -3069,6 +3069,8 @@ pub fn build_proc_header_new<'a, 'ctx, 'env>(
 ) -> FunctionValue<'ctx> {
     let layout = env.arena.alloc(layout).full();
 
+    dbg!(symbol, layout);
+
     build_proc_header(env, layout_ids, symbol, &layout, proc)
 }
 
diff --git a/compiler/mono/src/ir.rs b/compiler/mono/src/ir.rs
index 762796505a..c636f46c4e 100644
--- a/compiler/mono/src/ir.rs
+++ b/compiler/mono/src/ir.rs
@@ -7524,6 +7524,7 @@ fn lowlevel_match_on_lambda_set<'a, F>(
 where
     F: Fn(Symbol, Symbol) -> Call<'a> + Copy,
 {
+    dbg!(lambda_set);
     match dbg!(lambda_set.runtime_representation()) {
         Layout::Union(_) => {
             let closure_tag_id_symbol = env.unique_symbol();
diff --git a/compiler/test_gen/src/gen_list.rs b/compiler/test_gen/src/gen_list.rs
index 96cddca5c8..4ec2a79c99 100644
--- a/compiler/test_gen/src/gen_list.rs
+++ b/compiler/test_gen/src/gen_list.rs
@@ -1807,10 +1807,20 @@ fn list_keep_errs() {
     assert_evals_to!("List.keepErrs [] (\\x -> x)", 0, i64);
     assert_evals_to!("List.keepErrs [1,2] (\\x -> Err x)", &[1, 2], &[i64]);
     assert_evals_to!(
-        "List.keepErrs [0,1,2] (\\x -> x % 0 |> Result.mapErr (\\_ -> 32))",
+        indoc!(
+            r#"
+            mapErr = \result, f ->
+                when result is
+                    Err e -> Err ( f e )
+                    Ok v -> Ok v
+
+            List.keepErrs [0,1,2] (\x -> x % 0 |> mapErr (\_ -> 32))
+            "#
+        ),
         &[32, 32, 32],
         &[i64]
     );
+
     assert_evals_to!("List.keepErrs [Ok 1, Err 2] (\\x -> x)", &[2], &[i64]);
 }