diff --git a/compiler/can/src/builtins.rs b/compiler/can/src/builtins.rs
index 6e617bc60c..f719233c69 100644
--- a/compiler/can/src/builtins.rs
+++ b/compiler/can/src/builtins.rs
@@ -88,6 +88,7 @@ pub fn builtin_defs_map(symbol: Symbol, var_store: &mut VarStore) -> Option<Def>
         LIST_MAP3 => list_map3,
         LIST_DROP => list_drop,
         LIST_DROP_AT => list_drop_at,
+        LIST_DROP_LAST => list_drop_last,
         LIST_SWAP => list_swap,
         LIST_MAP_WITH_INDEX => list_map_with_index,
         LIST_KEEP_IF => list_keep_if,
@@ -2007,6 +2008,11 @@ fn list_drop_at(symbol: Symbol, var_store: &mut VarStore) -> Def {
 /// List.dropLast: List elem -> List elem
 fn list_drop_last(symbol: Symbol, var_store: &mut VarStore) -> Def {
     let list_var = var_store.fresh();
+    let index_var = var_store.fresh();
+    let arg_var = var_store.fresh();
+    let len_var = Variable::NAT;
+    let num_var = len_var;
+    let num_precision_var = Variable::NATURAL;
 
     let body = RunLowLevel {
         op: LowLevel::ListDropAt,
diff --git a/compiler/mono/src/borrow.rs b/compiler/mono/src/borrow.rs
index f09ac825c4..55fd53f18b 100644
--- a/compiler/mono/src/borrow.rs
+++ b/compiler/mono/src/borrow.rs
@@ -947,7 +947,6 @@ pub fn lowlevel_borrow_signature(arena: &Bump, op: LowLevel) -> &[bool] {
         ListAppend => arena.alloc_slice_copy(&[owned, owned]),
         ListDrop => arena.alloc_slice_copy(&[owned, irrelevant]),
         ListDropAt => arena.alloc_slice_copy(&[owned, irrelevant]),
-        ListDropLast => arena.alloc_slice_copy(&[owned]),
         ListSwap => arena.alloc_slice_copy(&[owned, irrelevant, irrelevant]),
 
         Eq | NotEq => arena.alloc_slice_copy(&[borrowed, borrowed]),