diff --git a/radio/src/gui/gui_common.cpp b/radio/src/gui/gui_common.cpp
index 6e2a6a19d..7a0388eb2 100644
--- a/radio/src/gui/gui_common.cpp
+++ b/radio/src/gui/gui_common.cpp
@@ -615,7 +615,7 @@ bool isExternalModuleAvailable(int moduleType)
   if (moduleType == MODULE_TYPE_ISRM_PXX2)
     return false; // doesn't exist for now
 
-#if !defined(PXX2)
+#if !defined(PXX2) || !defined(EXTMODULE_USART)
   if (moduleType == MODULE_TYPE_XJT_LITE_PXX2 || moduleType == MODULE_TYPE_R9M_PXX2 || moduleType == MODULE_TYPE_R9M_LITE_PXX2 || moduleType == MODULE_TYPE_R9M_LITE_PRO_PXX2) {
     return false;
   }
diff --git a/radio/src/pulses/pulses.cpp b/radio/src/pulses/pulses.cpp
index 7a8cae8ac..0703417c6 100755
--- a/radio/src/pulses/pulses.cpp
+++ b/radio/src/pulses/pulses.cpp
@@ -174,7 +174,7 @@ void enablePulsesExternalModule(uint8_t protocol)
       break;
 #endif
 
-#if defined(PXX2)
+#if defined(PXX2) && defined(EXTMODULE_USART)
     case PROTOCOL_CHANNELS_PXX2_HIGHSPEED:
       extmoduleInvertedSerialStart(PXX2_HIGHSPEED_BAUDRATE);
       break;
diff --git a/radio/src/targets/horus/extmodule_driver.cpp b/radio/src/targets/horus/extmodule_driver.cpp
index 99c5f811f..f453fa022 100644
--- a/radio/src/targets/horus/extmodule_driver.cpp
+++ b/radio/src/targets/horus/extmodule_driver.cpp
@@ -309,7 +309,7 @@ void extmoduleSendNextFrame()
       break;
 #endif
 
-#if defined(PXX2)
+#if defined(PXX2) && defined(EXTMODULE_USART)
     case PROTOCOL_CHANNELS_PXX2_HIGHSPEED:
     case PROTOCOL_CHANNELS_PXX2_LOWSPEED:
       extmoduleSendBuffer(extmodulePulsesData.pxx2.getData(), extmodulePulsesData.pxx2.getSize());