diff --git a/compiler/gen/src/llvm/build_list.rs b/compiler/gen/src/llvm/build_list.rs
index 77ee9909bc..ab0e766f0e 100644
--- a/compiler/gen/src/llvm/build_list.rs
+++ b/compiler/gen/src/llvm/build_list.rs
@@ -1,6 +1,9 @@
-use crate::llvm::build::{build_num_binop, Env, InPlace};
+use crate::llvm::build::{
+    allocate_with_refcount_help, build_num_binop, cast_basic_basic, Env, InPlace,
+};
 use crate::llvm::compare::build_eq;
 use crate::llvm::convert::{basic_type_from_layout, collection, get_ptr_type, ptr_int};
+use crate::llvm::refcounting::PointerToRefcount;
 use inkwell::builder::Builder;
 use inkwell::context::Context;
 use inkwell::types::{BasicTypeEnum, PointerType};
@@ -1894,53 +1897,13 @@ pub fn allocate_list<'a, 'ctx, 'env>(
     let builder = env.builder;
     let ctx = env.context;
 
-    let elem_type = basic_type_from_layout(env.arena, ctx, elem_layout, env.ptr_bytes);
-    let elem_bytes = elem_layout.stack_size(env.ptr_bytes) as u64;
-
     let len_type = env.ptr_int();
-    // bytes per element
-    let bytes_len = len_type.const_int(elem_bytes, false);
-    let offset = (env.ptr_bytes as u64).max(elem_bytes);
+    let elem_bytes = elem_layout.stack_size(env.ptr_bytes) as u64;
+    let bytes_per_element = len_type.const_int(elem_bytes, false);
 
-    let ptr = {
-        let len = builder.build_int_mul(bytes_len, length, "data_length");
-        let len =
-            builder.build_int_add(len, len_type.const_int(offset, false), "add_refcount_space");
+    let number_of_data_bytes = builder.build_int_mul(bytes_per_element, length, "data_length");
 
-        env.builder
-            .build_array_malloc(ctx.i8_type(), len, "create_list_ptr")
-            .unwrap()
-
-        // TODO check if malloc returned null; if so, runtime error for OOM!
-    };
-
-    // We must return a pointer to the first element:
-    let ptr_bytes = env.ptr_bytes;
-    let int_type = ptr_int(ctx, ptr_bytes);
-    let ptr_as_int = builder.build_ptr_to_int(ptr, int_type, "list_cast_ptr");
-    let incremented = builder.build_int_add(
-        ptr_as_int,
-        ctx.i64_type().const_int(offset, false),
-        "increment_list_ptr",
-    );
-
-    let ptr_type = get_ptr_type(&elem_type, AddressSpace::Generic);
-    let list_element_ptr = builder.build_int_to_ptr(incremented, ptr_type, "list_cast_ptr");
-
-    // subtract ptr_size, to access the refcount
-    let refcount_ptr = builder.build_int_sub(
-        incremented,
-        ctx.i64_type().const_int(env.ptr_bytes as u64, false),
-        "refcount_ptr",
-    );
-
-    let refcount_ptr = builder.build_int_to_ptr(
-        refcount_ptr,
-        int_type.ptr_type(AddressSpace::Generic),
-        "make ptr",
-    );
-
-    let ref_count_one = match inplace {
+    let rc1 = match inplace {
         InPlace::InPlace => length,
         InPlace::Clone => {
             // the refcount of a new list is initially 1
@@ -1949,9 +1912,7 @@ pub fn allocate_list<'a, 'ctx, 'env>(
         }
     };
 
-    builder.build_store(refcount_ptr, ref_count_one);
-
-    list_element_ptr
+    allocate_with_refcount_help(env, elem_layout, number_of_data_bytes, rc1)
 }
 
 pub fn store_list<'a, 'ctx, 'env>(
diff --git a/compiler/gen/src/llvm/build_str.rs b/compiler/gen/src/llvm/build_str.rs
index 24b18a5943..24092ed851 100644
--- a/compiler/gen/src/llvm/build_str.rs
+++ b/compiler/gen/src/llvm/build_str.rs
@@ -56,9 +56,11 @@ pub fn str_split<'a, 'ctx, 'env>(
                     )
                     .into_int_value();
 
+                    // a pointer to the elements
                     let ret_list_ptr =
                         allocate_list(env, inplace, &Layout::Builtin(Builtin::Str), segment_count);
 
+                    // convert `*mut RocStr` to `*mut i128`
                     let ret_list_ptr_u128s = builder.build_bitcast(
                         ret_list_ptr,
                         ctx.i128_type().ptr_type(AddressSpace::Generic),