diff --git a/rust/ares_pma/c-src/btree.c b/rust/ares_pma/c-src/btree.c
index 4cfd9d7..d2449e9 100644
--- a/rust/ares_pma/c-src/btree.c
+++ b/rust/ares_pma/c-src/btree.c
@@ -1175,6 +1175,7 @@ _pending_nlist_merge(BT_state *state)
     src_head = src_head->next;
     free(prev);
   }
+  state->pending_nlist = 0;
 }
 
 static void