diff --git a/compiler/gen/src/llvm/build.rs b/compiler/gen/src/llvm/build.rs
index dfe4a31825..b42461d47d 100644
--- a/compiler/gen/src/llvm/build.rs
+++ b/compiler/gen/src/llvm/build.rs
@@ -604,7 +604,9 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
 
     match expr {
         Literal(literal) => build_exp_literal(env, literal),
-        RunLowLevel(op, symbols) => run_low_level(env, scope, parent, layout, *op, symbols),
+        RunLowLevel(op, symbols) => {
+            run_low_level(env, layout_ids, scope, parent, layout, *op, symbols)
+        }
 
         ForeignCall {
             foreign_symbol,
@@ -1165,12 +1167,10 @@ fn list_literal<'a, 'ctx, 'env>(
     let builder = env.builder;
 
     let len_u64 = elems.len() as u64;
-    let elem_bytes = elem_layout.stack_size(env.ptr_bytes) as u64;
 
     let ptr = {
-        let bytes_len = elem_bytes * len_u64;
         let len_type = env.ptr_int();
-        let len = len_type.const_int(bytes_len, false);
+        let len = len_type.const_int(len_u64, false);
 
         allocate_list(env, inplace, elem_layout, len)
 
@@ -2410,6 +2410,7 @@ pub static COLD_CALL_CONV: u32 = 9;
 
 fn run_low_level<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
     scope: &Scope<'a, 'ctx>,
     parent: FunctionValue<'ctx>,
     layout: &Layout<'a>,
@@ -2523,7 +2524,16 @@ fn run_low_level<'a, 'ctx, 'env>(
 
             let inplace = get_inplace_from_layout(layout);
 
-            list_map(env, inplace, parent, func, func_layout, list, list_layout)
+            list_map(
+                env,
+                layout_ids,
+                inplace,
+                parent,
+                func,
+                func_layout,
+                list,
+                list_layout,
+            )
         }
         ListKeepIf => {
             // List.keepIf : List elem, (elem -> Bool) -> List elem
diff --git a/compiler/gen/src/llvm/build_list.rs b/compiler/gen/src/llvm/build_list.rs
index 904c3f0fe9..f2bca58085 100644
--- a/compiler/gen/src/llvm/build_list.rs
+++ b/compiler/gen/src/llvm/build_list.rs
@@ -3,12 +3,13 @@ use crate::llvm::build::{
 };
 use crate::llvm::compare::build_eq;
 use crate::llvm::convert::{basic_type_from_layout, collection, get_ptr_type};
+use crate::llvm::refcounting::decrement_refcount_layout;
 use inkwell::builder::Builder;
 use inkwell::context::Context;
 use inkwell::types::{BasicTypeEnum, PointerType};
 use inkwell::values::{BasicValueEnum, FunctionValue, IntValue, PointerValue, StructValue};
 use inkwell::{AddressSpace, IntPredicate};
-use roc_mono::layout::{Builtin, Layout, MemoryMode};
+use roc_mono::layout::{Builtin, Layout, LayoutIds, MemoryMode};
 
 /// List.single : a -> List a
 pub fn list_single<'a, 'ctx, 'env>(
@@ -1320,6 +1321,7 @@ pub fn list_keep_if_help<'a, 'ctx, 'env>(
 /// List.map : List before, (before -> after) -> List after
 pub fn list_map<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
     inplace: InPlace,
     parent: FunctionValue<'ctx>,
     func: BasicValueEnum<'ctx>,
@@ -1365,7 +1367,11 @@ pub fn list_map<'a, 'ctx, 'env>(
 
                 incrementing_elem_loop(builder, ctx, parent, list_ptr, len, "#index", list_loop);
 
-                store_list(env, ret_list_ptr, len)
+                let result = store_list(env, ret_list_ptr, len);
+
+                decrement_refcount_layout(env, parent, layout_ids, list, list_layout);
+
+                result
             };
 
             if_list_is_not_empty(env, parent, non_empty_fn, list, list_layout, "List.map")
@@ -2044,6 +2050,7 @@ pub fn allocate_list<'a, 'ctx, 'env>(
     let elem_bytes = elem_layout.stack_size(env.ptr_bytes) as u64;
     let bytes_per_element = len_type.const_int(elem_bytes, false);
 
+    // dbg!(bytes_per_element, length);
     let number_of_data_bytes = builder.build_int_mul(bytes_per_element, length, "data_length");
 
     let rc1 = match inplace {