diff --git a/SerialPort.cpp b/SerialPort.cpp
index 71e6fcc..1b580f4 100644
--- a/SerialPort.cpp
+++ b/SerialPort.cpp
@@ -206,6 +206,13 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
     
   bool ysfLoDev  = (data[0U] & 0x08U) == 0x08U;
   bool simplex   = (data[0U] & 0x80U) == 0x80U;
+
+#if !defined(DUPLEX)
+  if  (!simplex) {
+    DEBUG1("Full duplex not supported with this firmware");
+    return 6U;
+  }
+#endif
   
   m_debug = (data[0U] & 0x10U) == 0x10U;
 
diff --git a/version.h b/version.h
index d2eeecc..25ceb55 100644
--- a/version.h
+++ b/version.h
@@ -24,7 +24,7 @@
 
 #define VER_MAJOR       "1"
 #define VER_MINOR       "3"
-#define VER_REV         "1"
+#define VER_REV         "2"
 #define VERSION_DATE    "20180218"
 
 #if defined(ZUMSPOT_ADF7021)