diff --git a/companion/src/firmwares/opentx/opentxeeprom.cpp b/companion/src/firmwares/opentx/opentxeeprom.cpp
index 497b57f3c..c42e80483 100644
--- a/companion/src/firmwares/opentx/opentxeeprom.cpp
+++ b/companion/src/firmwares/opentx/opentxeeprom.cpp
@@ -1908,7 +1908,7 @@ class ArmCustomFunctionField: public TransformedField {
           else if (fn.adjustMode == 2)
             fn.param = RawSource(SOURCE_TYPE_GVAR, value).toValue();
           else
-            fn.param = (int8_t)value;
+            fn.param = (int16_t)value;
         }
         else if (version >= 214) {
           fn.adjustMode = _mode;
diff --git a/radio/src/gui/menu_model.cpp b/radio/src/gui/menu_model.cpp
index 9508e3278..ebea503a7 100644
--- a/radio/src/gui/menu_model.cpp
+++ b/radio/src/gui/menu_model.cpp
@@ -5128,7 +5128,7 @@ void menuModelCustomFunctions(uint8_t event)
           else if (func == FUNC_ADJUST_GVAR) {
             switch (CFN_GVAR_MODE(sd)) {
               case FUNC_ADJUST_GVAR_CONSTANT:
-                val_displayed = (int8_t)CFN_PARAM(sd);
+                val_displayed = (int16_t)CFN_PARAM(sd);
                 val_min = -CFN_GVAR_CST_MAX; val_max = +CFN_GVAR_CST_MAX;
                 lcd_outdezAtt(MODEL_CUSTOM_FUNC_3RD_COLUMN, y, val_displayed, attr|LEFT);
                 break;