diff --git a/frontend/src/content/config.ts b/frontend/src/content/config.ts
index 40afc1f..aacf66b 100644
--- a/frontend/src/content/config.ts
+++ b/frontend/src/content/config.ts
@@ -1,9 +1,9 @@
-import { RepoSummary } from '@lib/repo-summaries';
+import { RepoSummaryInContent } from '@lib/repo-summaries';
 import { defineCollection } from 'astro:content';
 
 const githubCollection = defineCollection({
   type: "data",
-  schema: RepoSummary,
+  schema: RepoSummaryInContent,
 });
 
 export const collections = {
diff --git a/frontend/src/lib/repo-summaries.ts b/frontend/src/lib/repo-summaries.ts
index 53e6f3b..53f0687 100644
--- a/frontend/src/lib/repo-summaries.ts
+++ b/frontend/src/lib/repo-summaries.ts
@@ -4,17 +4,23 @@ import { z } from 'zod';
 export const SloType = z.enum(["triage", "urgent", "important", "none"]);
 export type SloType = z.infer<typeof SloType>;
 
+const checkInstant = z.string().refine(val => {
+    try { Temporal.Instant.from(val); return true; } catch { return false; }
+});
+const checkDuration = z.string().refine(val => {
+    try { Temporal.Duration.from(val); return true; } catch { return false; }
+});
 const duration = z.string().transform(val => Temporal.Duration.from(val));
 const instant = z.string().transform(val => Temporal.Instant.from(val));
 
-export const IssueSummary = z.object({
+export const IssueSummaryInContent = z.object({
     url: z.string().url(),
     title: z.string(),
     author: z.string().optional(),
-    createdAt: instant,
+    createdAt: checkInstant,
     pull_request: z.object({ draft: z.boolean().default(false) }).optional(),
     labels: z.array(z.string()),
-    sloTimeUsed: duration,
+    sloTimeUsed: checkDuration,
     whichSlo: SloType,
     stats: z.object({
         numTimelineItems: z.number(),
@@ -22,13 +28,19 @@ export const IssueSummary = z.object({
         numLabels: z.number(),
     }).optional(),
 })
+export type IssueSummaryInContent = z.infer<typeof IssueSummaryInContent>;
+
+export const IssueSummary = IssueSummaryInContent.extend({
+    createdAt: instant,
+    sloTimeUsed: duration,
+});
 export type IssueSummary = z.infer<typeof IssueSummary>;
 
-export const RepoSummary = z.object({
-    cachedAt: instant,
+export const RepoSummaryInContent = z.object({
+    cachedAt: checkInstant,
     org: z.string(),
     repo: z.string(),
-    issues: IssueSummary.array(),
+    issues: IssueSummaryInContent.array(),
     labelsPresent: z.boolean(),
     stats: z.object({
         numLabels: z.number(),
@@ -36,4 +48,10 @@ export const RepoSummary = z.object({
         numPRs: z.number(),
     }).optional(),
 });
+export type RepoSummaryInContent = z.infer<typeof RepoSummaryInContent>;
+
+export const RepoSummary = RepoSummaryInContent.extend({
+    cachedAt: instant,
+    issues: IssueSummary.array(),
+});
 export type RepoSummary = z.infer<typeof RepoSummary>;
diff --git a/frontend/src/pages/[org]/[repo].astro b/frontend/src/pages/[org]/[repo].astro
index 0fc1924..c14911d 100644
--- a/frontend/src/pages/[org]/[repo].astro
+++ b/frontend/src/pages/[org]/[repo].astro
@@ -1,6 +1,7 @@
 ---
 import Issue from "@components/Issue.astro";
 import Layout from "@layouts/Layout.astro";
+import { IssueSummary } from "@lib/repo-summaries";
 import { cmpByTimeUsed, groupBySlo } from "@lib/slo";
 import type {
 GetStaticPaths,
@@ -30,7 +31,7 @@ const {
     importantViolations,
     urgent,
     urgentViolations,
-} = groupBySlo(details.issues);
+} = groupBySlo(IssueSummary.array().parse(details.issues));
 urgent.push(...urgentViolations);
 urgent.sort(cmpByTimeUsed);
 important.push(...importantViolations);
diff --git a/frontend/src/pages/index.astro b/frontend/src/pages/index.astro
index 00a06fc..374ab44 100644
--- a/frontend/src/pages/index.astro
+++ b/frontend/src/pages/index.astro
@@ -4,6 +4,7 @@ import { groupBySlo } from "@lib/slo";
 import * as ghLabels from "@lib/triage-labels";
 import { getCollection } from "astro:content";
 import Layout from "../layouts/Layout.astro";
+import { IssueSummary } from "@lib/repo-summaries";
 
 const repos = await getCollection("github");
 
@@ -21,7 +22,7 @@ const andFormatter = new Intl.ListFormat("en", {
 });
 
 const repoSummaries = repos.map((repo) => {
-    const groups = groupBySlo(repo.data.issues);
+    const groups = groupBySlo(IssueSummary.array().parse(repo.data.issues));
 
     const triageViolations = groups.triageViolations.length;
     const urgentViolations = groups.urgentViolations.length;