diff --git a/radio/src/functions.cpp b/radio/src/functions.cpp
index 01f405303..c337ae0b9 100644
--- a/radio/src/functions.cpp
+++ b/radio/src/functions.cpp
@@ -406,7 +406,7 @@ void evalFunctions(CustomFunctionData * functions, CustomFunctionsContext & func
               break;
             }
 
-            getvalue_t raw = getValue(CFN_PARAM(cfn));
+            getvalue_t raw = limit(-RESX, (int)getValue(CFN_PARAM(cfn)), RESX);
 #if defined(COLORLCD)
             requiredBacklightBright = BACKLIGHT_LEVEL_MAX - (g_eeGeneral.blOffBright +
                 ((1024 + raw) * ((BACKLIGHT_LEVEL_MAX - g_eeGeneral.backlightBright) - g_eeGeneral.blOffBright) / 2048));