diff --git a/esp/src/src-react/components/Logs.tsx b/esp/src/src-react/components/Logs.tsx
index a6295657dd8..02fcd0e80a6 100644
--- a/esp/src/src-react/components/Logs.tsx
+++ b/esp/src/src-react/components/Logs.tsx
@@ -137,7 +137,11 @@ export const Logs: React.FunctionComponent<LogsProps> = ({
                 formatter: ts => {
                     if (ts) {
                         if (ts.indexOf(":") < 0) {
-                            return timestampToDate(ts).toISOString();
+                            const date = timestampToDate(ts);
+                            if (!isNaN(date.getTime())) {
+                                return date.toISOString();
+                            }
+                            return ts;
                         }
                         return formatDateString(ts);
                     }