diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index c841f9fc6..d0c5bf556 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -871,7 +871,7 @@ mod pure_builtins {
         }
 
         let end = if len < 0 {
-            x.as_str().len() as usize
+            x.as_str().len()
         } else {
             cmp::min(beg + (len as usize), x.as_str().len())
         };