From 6f1185011f68a3989b5f1364f4d269961bb63050 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 5 Jan 2026 09:04:12 -1000
Subject: [PATCH] [bthome_mithermometer] Reduce heap allocations with
 stack-based string formatting

---
 esphome/components/bthome_mithermometer/bthome_ble.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/esphome/components/bthome_mithermometer/bthome_ble.cpp b/esphome/components/bthome_mithermometer/bthome_ble.cpp
index 762fc68b037..d1c51658962 100644
--- a/esphome/components/bthome_mithermometer/bthome_ble.cpp
+++ b/esphome/components/bthome_mithermometer/bthome_ble.cpp
@@ -4,6 +4,7 @@
 #include "esphome/core/log.h"
 
 #include <array>
+#include <span>
 
 #ifdef USE_ESP32
 
@@ -12,14 +13,14 @@ namespace bthome_mithermometer {
 
 static const char *const TAG = "bthome_mithermometer";
 
-static const char *format_mac_address(char *buffer, uint64_t address) {
+static const char *format_mac_address(std::span<char, MAC_ADDRESS_PRETTY_BUFFER_SIZE> buffer, uint64_t address) {
   std::array<uint8_t, MAC_ADDRESS_SIZE> mac{};
   for (size_t i = 0; i < MAC_ADDRESS_SIZE; i++) {
     mac[i] = (address >> ((MAC_ADDRESS_SIZE - 1 - i) * 8)) & 0xFF;
   }
 
-  format_mac_addr_upper(mac.data(), buffer);
-  return buffer;
+  format_mac_addr_upper(mac.data(), buffer.data());
+  return buffer.data();
 }
 
 static bool get_bthome_value_length(uint8_t obj_type, size_t &value_length) {