diff --git a/src/infra/format-time/format-duration.ts b/src/infra/format-time/format-duration.ts
index 4f486c38094..be706686f0e 100644
--- a/src/infra/format-time/format-duration.ts
+++ b/src/infra/format-time/format-duration.ts
@@ -32,7 +32,7 @@ export function formatDurationPrecise(
     return "unknown";
   }
   if (ms < 1000) {
-    return `${ms}ms`;
+    return `${Math.max(0, Math.round(ms))}ms`;
   }
   return formatDurationSeconds(ms, {
     decimals: options.decimals ?? 2,
diff --git a/src/infra/format-time/format-time.test.ts b/src/infra/format-time/format-time.test.ts
index f3fddff7f6d..b30c2a43135 100644
--- a/src/infra/format-time/format-time.test.ts
+++ b/src/infra/format-time/format-time.test.ts
@@ -90,6 +90,12 @@ describe("format-duration", () => {
       expect(formatDurationPrecise(999)).toBe("999ms");
     });
 
+    it("clamps negative and fractional sub-second values to non-negative milliseconds", () => {
+      expect(formatDurationPrecise(-1)).toBe("0ms");
+      expect(formatDurationPrecise(-500)).toBe("0ms");
+      expect(formatDurationPrecise(999.6)).toBe("1000ms");
+    });
+
     it("shows decimal seconds for >=1s", () => {
       expect(formatDurationPrecise(1000)).toBe("1s");
       expect(formatDurationPrecise(1500)).toBe("1.5s");