diff --git a/compiler/gen_llvm/src/llvm/build.rs b/compiler/gen_llvm/src/llvm/build.rs
index dc6b85042e..70d9c5a32f 100644
--- a/compiler/gen_llvm/src/llvm/build.rs
+++ b/compiler/gen_llvm/src/llvm/build.rs
@@ -5363,12 +5363,6 @@ fn run_low_level<'a, 'ctx, 'env>(
 
             str_trim_right(env, scope, args[0])
         }
-        StrToNum => {
-            // Str.toNum : Str -> Result (Num a) [ ExpectedNum a ]*
-            debug_assert_eq!(args.len(), 1);
-
-            str_to_num(env, scope, args[0])
-        }
         ListLen => {
             // List.len : List * -> Int
             debug_assert_eq!(args.len(), 1);
diff --git a/compiler/mono/src/borrow.rs b/compiler/mono/src/borrow.rs
index a0c0b71f01..abdbea8cec 100644
--- a/compiler/mono/src/borrow.rs
+++ b/compiler/mono/src/borrow.rs
@@ -943,8 +943,8 @@ pub fn lowlevel_borrow_signature(arena: &Bump, op: LowLevel) -> &[bool] {
         StrTrim => arena.alloc_slice_copy(&[owned]),
         StrTrimLeft => arena.alloc_slice_copy(&[owned]),
         StrTrimRight => arena.alloc_slice_copy(&[owned]),
-        StrToNum => arena.alloc_slice_copy(&[borrowed]), // TODO should this be borrowed?
         StrSplit => arena.alloc_slice_copy(&[borrowed, borrowed]),
+        StrToNum => arena.alloc_slice_copy(&[borrowed]),
         ListSingle => arena.alloc_slice_copy(&[irrelevant]),
         ListRepeat => arena.alloc_slice_copy(&[irrelevant, borrowed]),
         ListReverse => arena.alloc_slice_copy(&[owned]),