diff --git a/radio/src/targets/simu/simpgmspace.cpp b/radio/src/targets/simu/simpgmspace.cpp
index 3dae414d7..e22a9e3ee 100644
--- a/radio/src/targets/simu/simpgmspace.cpp
+++ b/radio/src/targets/simu/simpgmspace.cpp
@@ -759,7 +759,7 @@ AuxSerialRxFifo auxSerialRxFifo;
 #endif
 uint8_t auxSerialMode;
 
-void auxSerialSetup(unsigned int baudrate, bool dma, uint16_t length, uint16_t parity, uint16_t stop)
+void auxSerialSetup(unsigned int baudrate, bool dma, uint8_t length, uint8_t parity, uint8_t stop)
 {
 }
 
@@ -784,7 +784,7 @@ void auxSerialStop()
 AuxSerialRxFifo aux2SerialRxFifo(nullptr);
 uint8_t aux2SerialMode;
 
-void aux2SerialSetup(unsigned int baudrate, bool dma, uint16_t length, uint16_t parity, uint16_t stop)
+void aux2SerialSetup(unsigned int baudrate, bool dma, uint8_t length, uint8_t parity, uint8_t stop)
 {
 }