diff --git a/src/uart/emsuart_esp32.cpp b/src/uart/emsuart_esp32.cpp
index 4bf88d954..63cc8a9fa 100644
--- a/src/uart/emsuart_esp32.cpp
+++ b/src/uart/emsuart_esp32.cpp
@@ -67,8 +67,10 @@ void IRAM_ATTR EMSuart::emsuart_rx_intr_handler(void * para) {
                 drop_next_rx_ = true; // we have a overflow
             }
         }
-        if (rxbuf[length - 1]) { // check if last byte is break
-            length++;
+        if (length > 0 && length < EMS_MAXBUFFERSIZE) {
+            if (rxbuf[length - 1]) { // check if last byte is break
+                length++;
+            }
         }
         if ((!drop_next_rx_) && ((length == 2) || (length > 4))) {
             int baseType = 0;
diff --git a/src/uart/emsuart_esp32.h b/src/uart/emsuart_esp32.h
index 61b1bcb47..2eaad94be 100644
--- a/src/uart/emsuart_esp32.h
+++ b/src/uart/emsuart_esp32.h
@@ -46,10 +46,10 @@
 #define EMS_TXMODE_HW 4
 
 // LEGACY
-#define EMSUART_TX_BIT_TIME 104                             // bit time @9600 baud
+#define EMSUART_TX_BIT_TIME 104 // bit time @9600 baud
 
 // EMS 1.0
-#define EMSUART_TX_BUSY_WAIT (EMSUART_TX_BIT_TIME / 8)                       // 13
+#define EMSUART_TX_BUSY_WAIT (EMSUART_TX_BIT_TIME / 8) // 13
 #define EMSUART_TX_TIMEOUT (20 * EMSUART_TX_BIT_TIME / EMSUART_TX_BUSY_WAIT)
 #define EMSUART_TX_BRK_EMS (EMSUART_TX_BIT_TIME * 10)