diff --git a/compiler/can/src/builtins.rs b/compiler/can/src/builtins.rs
index 422dd9f76b..349cac6f80 100644
--- a/compiler/can/src/builtins.rs
+++ b/compiler/can/src/builtins.rs
@@ -1564,7 +1564,7 @@ fn str_from_utf8_range(symbol: Symbol, var_store: &mut VarStore) -> Def {
         branch_var: ret_var,
         branches: vec![(
             no_region(RunLowLevel {
-                op: LowLevel::NumLt,
+                op: LowLevel::NumLte,
                 args: vec![
                     (
                         bounds_var,