diff --git a/src/board_gruvin9x.cpp b/src/board_gruvin9x.cpp
index b4a6ea5b2..40dbf3406 100644
--- a/src/board_gruvin9x.cpp
+++ b/src/board_gruvin9x.cpp
@@ -32,7 +32,7 @@
  */
 
 #include "open9x.h"
-
+#ifndef SIMU
 inline void board_init()
 {
   // Set up I/O port data directions and initial states
@@ -67,6 +67,7 @@ inline void board_init()
   TCCR0B  = (1<<WGM02) | (0b011 << CS00);
   TCCR0A  = (0b01<<WGM00);
 }
+#endif
 
 FORCEINLINE uint8_t keyDown()
 {
diff --git a/src/board_stock.cpp b/src/board_stock.cpp
index bd712ac17..6da398cbe 100644
--- a/src/board_stock.cpp
+++ b/src/board_stock.cpp
@@ -33,6 +33,7 @@
 
 #include "open9x.h"
 
+#ifndef SIMU
 inline void board_init()
 {
   // Set up I/O port data directions and initial states
@@ -65,6 +66,7 @@ inline void board_init()
   TIMSK |= (1<<OCIE0) |  (1<<TOIE0); // Enable Output-Compare and Overflow interrrupts
   /********************************/
 }
+#endif
 
 FORCEINLINE uint8_t keyDown()
 {
diff --git a/src/drivers.cpp b/src/drivers.cpp
index 424bc3a47..45a2b25f5 100644
--- a/src/drivers.cpp
+++ b/src/drivers.cpp
@@ -258,7 +258,7 @@ void per10ms()
 #if defined(AUDIO)
     uint8_t warble = 0;
 #endif
-    int8_t verticalSpeed = limit((int16_t)-100, frskyHubData.varioSpeed/10, (int16_t)+100);
+    int8_t verticalSpeed = limit((int16_t)-100, (int16_t)(frskyHubData.varioSpeed/10), (int16_t)+100);
 
     uint16_t interval;
     if (verticalSpeed == 0) {