diff --git a/radio/src/targets/sky9x/serial2_driver.cpp b/radio/src/targets/sky9x/serial2_driver.cpp
index b7a749ff7..e2ee724fc 100644
--- a/radio/src/targets/sky9x/serial2_driver.cpp
+++ b/radio/src/targets/sky9x/serial2_driver.cpp
@@ -121,6 +121,6 @@ bool telemetrySecondPortReceive(uint8_t & data)
 }
 #endif
 
-#if defined(DEBUG)
+#if defined(DEBUG) && !defined(SIMU)
 void serialPrintf(const char*, ... ) {}
 #endif