diff --git a/framework_lib/src/chromium_ec/commands.rs b/framework_lib/src/chromium_ec/commands.rs
index cc04d33..1ee9b12 100644
--- a/framework_lib/src/chromium_ec/commands.rs
+++ b/framework_lib/src/chromium_ec/commands.rs
@@ -246,6 +246,16 @@ impl EcRequest<()> for EcRequestPwmSetFanDutyV1 {
 
 pub const PWM_MAX_DUTY: u16 = 0xFFFF;
 
+pub fn percent_to_duty(percent: u8) -> u16 {
+    let duty = percent as u32 * PWM_MAX_DUTY as u32;
+    (duty / 100) as u16
+}
+
+pub fn duty_to_percent(duty: u16) -> u8 {
+    let percent = duty as u32 * 100;
+    (percent / PWM_MAX_DUTY as u32) as u8
+}
+
 #[repr(C, packed)]
 pub struct EcRequestPwmSetDuty {
     /// Duty cycle, min 0, max 0xFFFF
diff --git a/framework_lib/src/chromium_ec/mod.rs b/framework_lib/src/chromium_ec/mod.rs
index 2aa9e67..2b3d7e9 100644
--- a/framework_lib/src/chromium_ec/mod.rs
+++ b/framework_lib/src/chromium_ec/mod.rs
@@ -770,24 +770,49 @@ impl CrosEc {
     /// * `percent` - An integer from 0 to 100. 0 being off, 100 being full brightness
     pub fn set_keyboard_backlight(&self, percent: u8) {
         debug_assert!(percent <= 100);
+        let duty = percent_to_duty(percent);
+
         let res = EcRequestPwmSetDuty {
-            duty: percent as u16 * (PWM_MAX_DUTY / 100),
+            duty,
             pwm_type: PwmType::KbLight as u8,
             index: 0,
         }
         .send_command(self);
+
+        // Early systems (hx20/hx30) don't enable CONFIG_PWM_KBLIGHT in their EC firmware;
+        // keyboard backlight is at generic PWM channel index 1.
+        let res = match res {
+            Err(EcError::Response(EcResponseStatus::InvalidParameter)) => EcRequestPwmSetDuty {
+                duty,
+                pwm_type: PwmType::Generic as u8,
+                index: 1,
+            }
+            .send_command(self),
+            other => other,
+        };
         debug_assert!(res.is_ok());
     }
 
     /// Check the current brightness of the keyboard backlight
     pub fn get_keyboard_backlight(&self) -> EcResult<u8> {
-        let kblight = EcRequestPwmGetDuty {
+        let res = EcRequestPwmGetDuty {
             pwm_type: PwmType::KbLight as u8,
             index: 0,
         }
-        .send_command(self)?;
+        .send_command(self);
+
+        // Early systems (hx20/hx30) don't enable CONFIG_PWM_KBLIGHT in their EC firmware;
+        // keyboard backlight is at generic PWM channel index 1.
+        let kblight = match res {
+            Err(EcError::Response(EcResponseStatus::InvalidParameter)) => EcRequestPwmGetDuty {
+                pwm_type: PwmType::Generic as u8,
+                index: 1,
+            }
+            .send_command(self)?,
+            other => other?,
+        };
 
-        Ok((kblight.duty / (PWM_MAX_DUTY / 100)) as u8)
+        Ok(duty_to_percent(kblight.duty))
     }
 
     pub fn ps2_emulation_enable(&self, enable: bool) -> EcResult<()> {
diff --git a/framework_lib/src/commandline/mod.rs b/framework_lib/src/commandline/mod.rs
index d965b67..7114c7a 100644
--- a/framework_lib/src/commandline/mod.rs
+++ b/framework_lib/src/commandline/mod.rs
@@ -1430,8 +1430,11 @@ pub fn run_with_args(args: &Cli, _allupdate: bool) -> i32 {
     } else if let Some(maybe_brightness) = &args.fp_brightness {
         print_err(handle_fp_brightness(&ec, *maybe_brightness));
     } else if let Some(Some(kblight)) = args.kblight {
-        assert!(kblight <= 100);
-        ec.set_keyboard_backlight(kblight);
+        if kblight > 100 {
+            error!("--kblight must be percentage 0-100");
+        } else {
+            ec.set_keyboard_backlight(kblight);
+        }
     } else if let Some(None) = args.kblight {
         print!("Keyboard backlight: ");
         if let Some(percentage) = print_err(ec.get_keyboard_backlight()) {