diff --git a/esphome/components/zwave_proxy/zwave_proxy.cpp b/esphome/components/zwave_proxy/zwave_proxy.cpp
index 8506b19e7f..b0836ac072 100644
--- a/esphome/components/zwave_proxy/zwave_proxy.cpp
+++ b/esphome/components/zwave_proxy/zwave_proxy.cpp
@@ -281,6 +281,10 @@ bool ZWaveProxy::parse_byte_(uint8_t byte) {
       break;
     }
     case ZWAVE_PARSING_STATE_READ_BL_MENU:
+      if (this->buffer_index_ >= this->buffer_.size()) {
+        this->parsing_state_ = ZWAVE_PARSING_STATE_WAIT_START;
+        break;
+      }
       this->buffer_[this->buffer_index_++] = byte;
       if (!byte) {
         this->parsing_state_ = ZWAVE_PARSING_STATE_WAIT_START;
diff --git a/esphome/components/zwave_proxy/zwave_proxy.h b/esphome/components/zwave_proxy/zwave_proxy.h
index eb26316f49..12cb9a90a1 100644
--- a/esphome/components/zwave_proxy/zwave_proxy.h
+++ b/esphome/components/zwave_proxy/zwave_proxy.h
@@ -81,10 +81,10 @@ class ZWaveProxy : public uart::UARTDevice, public Component {
   api::APIConnection *api_connection_{nullptr};  // Current subscribed client
   uint32_t setup_time_{0};                       // Time when setup() was called
 
-  // 8-bit values (grouped together to minimize padding)
-  uint8_t buffer_index_{0};     // Index for populating the data buffer
-  uint8_t end_frame_after_{0};  // Payload reception ends after this index
-  uint8_t last_response_{0};    // Last response type sent
+  // Small values (grouped by size to minimize padding)
+  uint16_t buffer_index_{0};     // Index for populating the data buffer
+  uint16_t end_frame_after_{0};  // Payload reception ends after this index
+  uint8_t last_response_{0};     // Last response type sent
   ZWaveParsingState parsing_state_{ZWAVE_PARSING_STATE_WAIT_START};
   bool in_bootloader_{false};  // True if the device is detected to be in bootloader mode
   bool home_id_ready_{false};  // True when home ID has been received from Z-Wave module