diff --git a/esphome/components/api/api_frame_helper_noise.cpp b/esphome/components/api/api_frame_helper_noise.cpp
index 97db5ae0b1..65f16ab3c8 100644
--- a/esphome/components/api/api_frame_helper_noise.cpp
+++ b/esphome/components/api/api_frame_helper_noise.cpp
@@ -267,7 +267,8 @@ APIError APINoiseFrameHelper::state_action_() {
     size_t mac_offset = name_offset + name_len;
     size_t total_size = 1 + name_len + MAC_ADDRESS_BUFFER_SIZE;
 
-    // 1 (proto) + name + null + mac + null
+    // 1 (proto) + name (max ESPHOME_DEVICE_NAME_MAX_LEN) + 1 (name null)
+    // + mac (MAC_ADDRESS_BUFFER_SIZE - 1) + 1 (mac null)
     constexpr size_t max_msg_size = 1 + ESPHOME_DEVICE_NAME_MAX_LEN + 1 + MAC_ADDRESS_BUFFER_SIZE;
     uint8_t msg[max_msg_size];