diff --git a/esphome/core/lwip_fast_select.c b/esphome/core/lwip_fast_select.c
index fa8981e140..4ccfed3f62 100644
--- a/esphome/core/lwip_fast_select.c
+++ b/esphome/core/lwip_fast_select.c
@@ -49,6 +49,8 @@
 // is single-writer for close. ESPHome guarantees this by design: all socket
 // create/read/close happens on the main loop. fd numbers are not reused while
 // the slot remains allocated, and the slot remains allocated until lwip_close().
+// Any change in LwIP that allows free_socket() to be called outside lwip_close()
+// would invalidate this assumption.
 //
 // LwIP source references for slot lifetime:
 //   sockets.c (same commit as above):