diff --git a/crates/ailang-codegen/src/match_lower.rs b/crates/ailang-codegen/src/match_lower.rs
index 7ec413f..aae6c6e 100644
--- a/crates/ailang-codegen/src/match_lower.rs
+++ b/crates/ailang-codegen/src/match_lower.rs
@@ -714,10 +714,23 @@ impl<'a> Emitter<'a> {
             // values that are now owned by downstream frames —
             // that's exactly the bug 18d.3's `moved_slots` was set
             // up to prevent.
-            let arm_body_is_tail_call = matches!(
-                &arm.body,
-                MTerm::App { tail: true, .. } | MTerm::Do { tail: true, .. }
-            );
+            // A tail call may be the arm body directly, or wrapped in a
+            // trailing `(let ...)` / `(seq ...)` chain whose tail-position
+            // sub-term (a `Let`'s body, a `Seq`'s rhs) is the tail call.
+            // `lower_term` descends through the wrapper and still emits the
+            // inner call as `musttail`, so the two drop-emission gates below
+            // (husk-dec, leg-1 owned-param dec) must fire for the wrapped
+            // form too — otherwise the scrutinee husk and the non-forwarded
+            // owned param each leak one slab per recursion step (#63, leg 2).
+            fn tail_position_is_tail_call(t: &MTerm) -> bool {
+                match t {
+                    MTerm::App { tail: true, .. } | MTerm::Do { tail: true, .. } => true,
+                    MTerm::Let { body, .. } => tail_position_is_tail_call(body),
+                    MTerm::Seq { rhs, .. } => tail_position_is_tail_call(rhs),
+                    _ => false,
+                }
+            }
+            let arm_body_is_tail_call = tail_position_is_tail_call(&arm.body);
             if matches!(self.alloc, AllocStrategy::Rc)
                 && arm_body_is_tail_call
                 && scrutinee_is_owned