diff --git a/src/components/Details.svelte b/src/components/Details.svelte
index 734c1f7..7e3eccc 100644
--- a/src/components/Details.svelte
+++ b/src/components/Details.svelte
@@ -23,7 +23,7 @@
 
   let voltsPerCell = $derived(batterySpecs.cellCount ? data.voltage / batterySpecs.cellCount : NaN);
   let cellVoltsLow = $derived(voltsPerCell && batterySpecs.cellMinVolt && voltsPerCell < batterySpecs.cellMinVolt);
-  let formatSpeed = $derived((x: number) => mapSpeed(x).toFixed(1));
+  let formatSpeed = $derived((x: number) => (Number.isNaN(x) ? '??' : mapSpeed(x).toFixed(1)));
 
   const getStateColor = (state: string): string | undefined => {
     switch (state.toLowerCase()) {
@@ -84,8 +84,16 @@
   <div class={itemClass}>
     <List
       items={[
-        { label: 'Duty', value: `${data.duty}%`, color: data.duty > 80 ? 'red' : ChartColours.DutyCycle },
-        { label: 'Motor Current', value: `${data.current_motor} A`, color: ChartColours.CurrentMotor },
+        {
+          label: 'Duty',
+          value: `${Number.isNaN(data.duty) ? '?? ' : data.duty}%`,
+          color: data.duty > 80 ? 'red' : ChartColours.DutyCycle,
+        },
+        {
+          label: 'Motor Current',
+          value: `${Number.isNaN(data.current_motor) ? '??' : data.current_motor} A`,
+          color: ChartColours.CurrentMotor,
+        },
         ...(Number.isNaN(data.current_field_weakening)
           ? []
           : [
@@ -107,13 +115,21 @@
       items={[
         { label: 'Spec', value: batterySpecs.cellCount ? `${batterySpecs.cellCount}S` : configureButton },
         '-',
-        { label: 'Batt V (total)', value: `${data.voltage} V`, color: ChartColours.BatteryVoltage },
+        {
+          label: 'Batt V (total)',
+          value: `${Number.isNaN(data.voltage) ? '?? ' : data.voltage} V`,
+          color: ChartColours.BatteryVoltage,
+        },
         {
           label: 'Batt V (cell)',
           value: `${voltsPerCell ? voltsPerCell.toFixed(1) : '??'} V`,
           color: cellVoltsLow ? 'red' : ChartColours.BatteryVoltage,
         },
-        { label: 'Batt Current', value: `${data.current_battery} A`, color: ChartColours.CurrentBattery },
+        {
+          label: 'Batt Current',
+          value: `${Number.isNaN(data.current_battery) ? '??' : data.current_battery} A`,
+          color: ChartColours.CurrentBattery,
+        },
       ]}
     />
   </div>
diff --git a/src/lib/parse/floaty.ts b/src/lib/parse/floaty.ts
index 4d5d2c7..07f068d 100644
--- a/src/lib/parse/floaty.ts
+++ b/src/lib/parse/floaty.ts
@@ -14,12 +14,12 @@ function rowsFromFloatyJson(json: ZFloatyJson): Row[] {
     bms_fault: NaN,
     bms_temp: NaN,
     bms_temp_battery: NaN,
-    current_battery: log.batteryCurrent,
+    current_battery: log.batteryCurrent ?? NaN,
     current_booster: NaN,
     current_field_weakening: NaN,
-    current_motor: log.motorCurrent,
+    current_motor: log.motorCurrent ?? NaN,
     distance: log.tripDistance,
-    duty: log.dutyCycle,
+    duty: log.dutyCycle ?? NaN,
     erpm: NaN,
     gps_accuracy: location.accuracy,
     gps_latitude: location.latitude,
@@ -34,7 +34,7 @@ function rowsFromFloatyJson(json: ZFloatyJson): Row[] {
     setpoint_remote: NaN,
     setpoint_torque_tilt: NaN,
     setpoint: NaN,
-    speed: log.speed,
+    speed: log.speed ?? NaN,
     state_raw: log.state,
     state: stateCodeMap[log.state] ?? '??',
     temp_battery: NaN,
@@ -42,7 +42,7 @@ function rowsFromFloatyJson(json: ZFloatyJson): Row[] {
     temp_motor: log.motorTemp,
     time: (log.timestamp - json.startTime) / 1000,
     true_pitch: log.truePitchAngle,
-    voltage: log.batteryVolts,
+    voltage: log.batteryVolts ?? NaN,
     wh_charged: NaN,
     wh: log.wattHours,
   });
diff --git a/src/lib/parse/floaty.types.ts b/src/lib/parse/floaty.types.ts
index 277e7b4..948ee51 100644
--- a/src/lib/parse/floaty.types.ts
+++ b/src/lib/parse/floaty.types.ts
@@ -13,12 +13,12 @@ export const LocationSchema = z.object({
 export type ZLog = z.infer<typeof LogSchema>;
 export const LogSchema = z.object({
   timestamp: z.number(),
-  speed: z.number(),
-  dutyCycle: z.number(),
-  batteryVolts: z.number(),
+  speed: z.number().nullable(),
+  dutyCycle: z.number().nullable(),
+  batteryVolts: z.number().nullable(),
   batteryPercent: z.number(),
-  batteryCurrent: z.number(),
-  motorCurrent: z.number(),
+  batteryCurrent: z.number().nullable(),
+  motorCurrent: z.number().nullable(),
   motorTemp: z.number(),
   controllerTemp: z.number(),
   tripDistance: z.number(),