diff --git a/src/lib/utils.check.ts b/src/lib/utils.check.ts
new file mode 100644
index 00000000..9977baf4
--- /dev/null
+++ b/src/lib/utils.check.ts
@@ -0,0 +1,16 @@
+/** Self-check for `formatMinutesSeconds`, which every playback time in the app goes through. */
+export {};
+
+import { formatMinutesSeconds } from "./utils";
+
+function check(actual: string, expected: string, message: string): void {
+  if (actual !== expected) throw new Error(`FAILED: ${message} (got ${actual}, want ${expected})`);
+}
+
+check(formatMinutesSeconds(225), "3:45", "under an hour stays m:ss, no leading zero");
+check(formatMinutesSeconds(59.9), "0:59", "fractions floor");
+check(formatMinutesSeconds(3725), "1:02:05", "an hour and up adds hours, padding minutes");
+check(formatMinutesSeconds(-1), "0:00", "a countdown that overshoots clamps to zero");
+check(formatMinutesSeconds(Number.NaN), "0:00", "an unknown duration reads as zero");
+
+console.log("formatMinutesSeconds: ok");
diff --git a/src/lib/utils.ts b/src/lib/utils.ts
index 6e76d768..8c7fbfe1 100644
--- a/src/lib/utils.ts
+++ b/src/lib/utils.ts
@@ -6,13 +6,16 @@ export function cn(...inputs: ClassValue[]) {
 }
 
 /**
- * `m:ss` for a whole-second duration. Callers round `seconds` themselves (floor for elapsed
- * position, ceil for a countdown) — this only formats what it's given.
+ * `m:ss` for a whole-second duration, `h:mm:ss` from an hour up. Callers round `seconds`
+ * themselves (floor for elapsed position, ceil for a countdown) — this only formats what it's given.
  */
 export function formatMinutesSeconds(seconds: number): string {
   if (!Number.isFinite(seconds)) return "0:00";
   const whole = Math.max(0, Math.floor(seconds));
-  const mins = Math.floor(whole / 60);
-  const secs = whole % 60;
-  return `${mins}:${secs.toString().padStart(2, "0")}`;
+  const hours = Math.floor(whole / 3600);
+  const mins = Math.floor((whole % 3600) / 60);
+  const secs = (whole % 60).toString().padStart(2, "0");
+  return hours > 0
+    ? `${hours}:${mins.toString().padStart(2, "0")}:${secs}`
+    : `${mins}:${secs}`;
 }
diff --git a/src/ui/components/player/SeekBar.tsx b/src/ui/components/player/SeekBar.tsx
index eadaf6a2..323872af 100644
--- a/src/ui/components/player/SeekBar.tsx
+++ b/src/ui/components/player/SeekBar.tsx
@@ -244,7 +244,7 @@ export function SeekBar() {
 
   return (
     <div className="group/seek flex w-full items-center gap-2.5">
-      <span className="w-10 shrink-0 text-right text-xs tabular-nums text-muted-foreground">
+      <span className="min-w-10 shrink-0 text-right text-xs tabular-nums text-muted-foreground">
         {formatTime(currentTime)}
       </span>
       <input
@@ -266,7 +266,7 @@ export function SeekBar() {
         } as React.CSSProperties}
         aria-label="Seek"
       />
-      <span className="w-10 shrink-0 text-xs tabular-nums text-muted-foreground">
+      <span className="min-w-10 shrink-0 text-xs tabular-nums text-muted-foreground">
         {formatTime(duration)}
       </span>
     </div>