diff --git a/output/src/ops/bsp.rs b/output/src/ops/bsp.rs
index fe48efc..300d244 100644
--- a/output/src/ops/bsp.rs
+++ b/output/src/ops/bsp.rs
@@ -25,9 +25,10 @@ try_from_expr!(<'source, 'state, E>: Bsp<RenderBox<'state, E>, RenderBox<'state,
     if let Some(Token { value: Value::Key(key), .. }) = iter.peek() {
         match key {
             "bsp/n"|"bsp/s"|"bsp/e"|"bsp/w"|"bsp/a"|"bsp/b" => {
-                let _ = iter.next().unwrap();
-                let c1 = iter.next().expect("no content1 specified");
-                let c2 = iter.next().expect("no content2 specified");
+                let original = iter.clone();
+                let _  = iter.next().unwrap();
+                let c1 = iter.next().unwrap_or_else(||panic!("no content1 specified: {original:?}"));
+                let c2 = iter.next().unwrap_or_else(||panic!("no content2 specified: {original:?}"));
                 let c1 = state.get_content(&c1.value).expect("no content1 provided");
                 let c2 = state.get_content(&c2.value).expect("no content2 provided");
                 return Some(match key {