diff --git a/src/main/msp/msp.c b/src/main/msp/msp.c
index 87136e8f9a..3087069b9d 100644
--- a/src/main/msp/msp.c
+++ b/src/main/msp/msp.c
@@ -255,6 +255,7 @@ static void mspEscPassthroughFn(serialPort_t *serialPort)
 }
 #endif
 
+#ifdef USE_SERIAL_PASSTHROUGH
 static serialPort_t *mspFindPassthroughSerialPort(void)
 {
     serialPortUsage_t *portUsage = NULL;