--- a/crates/jrsonnet-evaluator/src/builtin/mod.rs
+++ b/crates/jrsonnet-evaluator/src/builtin/mod.rs
@@ -283,6 +283,9 @@
 			0, from: [Val::Num]!!Val::Num, vec![ValType::Num];
 			1, to: [Val::Num]!!Val::Num, vec![ValType::Num];
 		], {
+			if to < from {
+				return Ok(Val::Arr(Rc::new(Vec::new())))
+			}
 			let mut out = Vec::with_capacity((1+to as usize-from as usize).max(0));
 			for i in from as usize..=to as usize {
 				out.push(Val::Num(i as f64));