diff --git a/radio/src/functions.cpp b/radio/src/functions.cpp
index 99516aef6..6fdd9b646 100644
--- a/radio/src/functions.cpp
+++ b/radio/src/functions.cpp
@@ -367,8 +367,10 @@ void evalFunctions()
             }
 #if defined(CPUARM)
             if (CFN_PARAM(cfn)>=FUNC_RESET_PARAM_FIRST_TELEM) {
-              TelemetryItem * telemetryItem = & telemetryItems[CFN_PARAM(cfn)-FUNC_RESET_PARAM_FIRST_TELEM];
-              telemetryItem->clear();
+              uint8_t item = CFN_PARAM(cfn)-FUNC_RESET_PARAM_FIRST_TELEM;
+              if (item < MAX_SENSORS) {
+                telemetryItems[item].clear();
+              }
             }
 #endif
             break;
diff --git a/radio/src/gui/9X/lcd.cpp b/radio/src/gui/9X/lcd.cpp
index f07ed892e..4e8d27ccb 100644
--- a/radio/src/gui/9X/lcd.cpp
+++ b/radio/src/gui/9X/lcd.cpp
@@ -881,6 +881,7 @@ void displayGpsCoords(coord_t x, coord_t y, TelemetryItem & telemetryItem, LcdFl
 
 void putsTelemetryChannelValue(coord_t x, coord_t y, uint8_t channel, lcdint_t value, LcdFlags att)
 {
+  if (channel >= MAX_SENSORS) return;
   TelemetryItem & telemetryItem = telemetryItems[channel];
   TelemetrySensor & telemetrySensor = g_model.telemetrySensors[channel];
   if (telemetrySensor.unit == UNIT_DATETIME) {
diff --git a/radio/src/gui/Taranis/lcd.cpp b/radio/src/gui/Taranis/lcd.cpp
index 738726564..6ef2339cc 100644
--- a/radio/src/gui/Taranis/lcd.cpp
+++ b/radio/src/gui/Taranis/lcd.cpp
@@ -952,6 +952,7 @@ void displayGpsCoords(coord_t x, coord_t y, TelemetryItem & telemetryItem, LcdFl
 
 void putsTelemetryChannelValue(coord_t x, coord_t y, uint8_t channel, lcdint_t value, LcdFlags att)
 {
+  if (channel >= MAX_SENSORS) return;     //Lua luaLcdDrawChannel() can call us with a bad value 
   TelemetryItem & telemetryItem = telemetryItems[channel];
   TelemetrySensor & telemetrySensor = g_model.telemetrySensors[channel];
   if (telemetrySensor.unit == UNIT_DATETIME) {
diff --git a/radio/src/gui/Taranis/view_main.cpp b/radio/src/gui/Taranis/view_main.cpp
index 4b6f9b256..b5a441d9d 100644
--- a/radio/src/gui/Taranis/view_main.cpp
+++ b/radio/src/gui/Taranis/view_main.cpp
@@ -236,22 +236,26 @@ void displayTopBar()
     /* Rx voltage */
     altitude_icon_x = batt_icon_x+7*FW+3;
     if (g_model.frsky.voltsSource) {
-      TelemetryItem & voltsItem = telemetryItems[g_model.frsky.voltsSource-1];
-      if (voltsItem.isAvailable()) {
-        putsTelemetryChannelValue(batt_icon_x+7*FW+2, BAR_Y+1, g_model.frsky.voltsSource-1, voltsItem.value, LEFT);
-        altitude_icon_x = lcdLastPos+1;
+      uint8_t item = g_model.frsky.voltsSource-1;
+      if (item < MAX_SENSORS) {
+        TelemetryItem & voltsItem = telemetryItems[item];
+        if (voltsItem.isAvailable()) {
+          putsTelemetryChannelValue(batt_icon_x+7*FW+2, BAR_Y+1, item, voltsItem.value, LEFT);
+          altitude_icon_x = lcdLastPos+1;
+        }
       }
     }
 
     /* Altitude */
     if (g_model.frsky.altitudeSource) {
-      TelemetryItem & altitudeItem = telemetryItems[g_model.frsky.altitudeSource-1];
-      if (altitudeItem.isAvailable()) {
-        LCD_ICON(altitude_icon_x, BAR_Y, ICON_ALTITUDE);
-        int32_t value = altitudeItem.value;
-        TelemetrySensor & sensor = g_model.telemetrySensors[g_model.frsky.altitudeSource-1];
-        if (sensor.prec) value /= sensor.prec == 2 ? 100 : 10;
-        putsValueWithUnit(altitude_icon_x+2*FW-1, BAR_Y+1, value, UNIT_METERS, LEFT);
+      uint8_t item = g_model.frsky.altitudeSource-1;
+      if (item < MAX_SENSORS) {
+        TelemetryItem & altitudeItem = telemetryItems[item];
+        if (altitudeItem.isAvailable()) {
+          LCD_ICON(altitude_icon_x, BAR_Y, ICON_ALTITUDE);
+          int32_t value = altitudeItem.value / g_model.telemetrySensors[item].getPrecDivisor();
+          putsValueWithUnit(altitude_icon_x+2*FW-1, BAR_Y+1, value, UNIT_METERS, LEFT);
+        }
       }
     }
   }
diff --git a/radio/src/lua_api.cpp b/radio/src/lua_api.cpp
index 4b2d99839..4c94ef1e9 100644
--- a/radio/src/lua_api.cpp
+++ b/radio/src/lua_api.cpp
@@ -196,7 +196,7 @@ static void luaGetValueAndPush(int src)
           break;
         default:
           if (telemetrySensor.prec > 0)
-            lua_pushnumber(L, float(value)/(telemetrySensor.prec == 2 ? 100.0 : 10.0));
+            lua_pushnumber(L, float(value)/telemetrySensor.getPrecDivisor());
           else
             lua_pushinteger(L, value);
           break;
diff --git a/radio/src/myeeprom.h b/radio/src/myeeprom.h
index dd86250ec..9417574de 100644
--- a/radio/src/myeeprom.h
+++ b/radio/src/myeeprom.h
@@ -1313,10 +1313,12 @@ PACK(typedef struct {
   };
   void init(const char *label, uint8_t unit=UNIT_RAW, uint8_t prec=0);
   void init(uint16_t id);
-  bool isAvailable();
+  bool isAvailable() const;
   int32_t getValue(int32_t value, uint8_t unit, uint8_t prec) const;
-  bool isConfigurable();
-  bool isPrecConfigurable();
+  bool isConfigurable() const;
+  bool isPrecConfigurable() const;
+  uint32_t getPrecMultiplier() const;
+  uint32_t getPrecDivisor() const;
 }) TelemetrySensor;
 #endif
 
diff --git a/radio/src/telemetry/telemetry.cpp b/radio/src/telemetry/telemetry.cpp
index 872e389c2..bbde9fd95 100644
--- a/radio/src/telemetry/telemetry.cpp
+++ b/radio/src/telemetry/telemetry.cpp
@@ -366,10 +366,7 @@ void TelemetryItem::eval(const TelemetrySensor & sensor)
         result += dist*dist;
 
         if (altItem) {
-          dist = abs(altItem->value);
-          uint8_t prec = g_model.telemetrySensors[sensor.dist.alt-1].prec;
-          if (prec > 0)
-            dist /= (prec==2 ? 100 : 10);
+          dist = abs(altItem->value) / g_model.telemetrySensors[sensor.dist.alt-1].getPrecDivisor();
           result += dist*dist;
         }
 
@@ -545,7 +542,7 @@ void TelemetrySensor::init(uint16_t id)
   init(label);
 }
 
-bool TelemetrySensor::isAvailable()
+bool TelemetrySensor::isAvailable() const
 {
   return ZLEN(label) > 0;
 }
@@ -622,7 +619,7 @@ int32_t TelemetrySensor::getValue(int32_t value, uint8_t unit, uint8_t prec) con
   return value;
 }
 
-bool TelemetrySensor::isConfigurable()
+bool TelemetrySensor::isConfigurable() const
 {
   if (type == TELEM_TYPE_CALCULATED) {
     if (formula >= TELEM_FORMULA_CELL) {
@@ -637,7 +634,7 @@ bool TelemetrySensor::isConfigurable()
   return true;
 }
 
-bool TelemetrySensor::isPrecConfigurable()
+bool TelemetrySensor::isPrecConfigurable() const
 {
   if (isConfigurable()) {
     return true;
@@ -649,3 +646,17 @@ bool TelemetrySensor::isPrecConfigurable()
     return false;
   }
 }
+
+uint32_t TelemetrySensor::getPrecMultiplier() const
+{
+  if (prec == 2) return 1;
+  if (prec == 1) return 10;
+  return 100;
+}
+
+uint32_t TelemetrySensor::getPrecDivisor() const
+{
+  if (prec == 2) return 100;
+  if (prec == 1) return 10;
+  return 1;
+}
diff --git a/radio/src/vario.cpp b/radio/src/vario.cpp
index 4d5d362e4..c410b2a5a 100644
--- a/radio/src/vario.cpp
+++ b/radio/src/vario.cpp
@@ -47,10 +47,10 @@ void varioWakeup()
 
     int verticalSpeed = 0;
     if (g_model.frsky.varioSource) {
-      TelemetryItem & varioItem = telemetryItems[g_model.frsky.varioSource-1];
-      verticalSpeed = varioItem.value;
-      TelemetrySensor & sensor = g_model.telemetrySensors[g_model.frsky.varioSource-1];
-      if (sensor.prec != 2) verticalSpeed *= sensor.prec == 0 ? 100 : 10;
+      uint8_t item = g_model.frsky.varioSource-1;
+      if (item < MAX_SENSORS) {
+        verticalSpeed = telemetryItems[item].value * g_model.telemetrySensors[item].getPrecMultiplier();
+      }
     }
 
     int varioCenterMin = (int)g_model.frsky.varioCenterMin * 10 - 50;