diff --git a/infra/api/src/index.ts b/infra/api/src/index.ts
index 72cd98c..9b31fe3 100644
--- a/infra/api/src/index.ts
+++ b/infra/api/src/index.ts
@@ -673,7 +673,7 @@ async function fanInExistingPosts(readerDid: string, authorDid: string, publicat
     const postRkey = (post.SK as string).slice('p#'.length);
     const item: Record<string, unknown> = {
       PK: `u#${readerDid}#timeline`,
-      SK: `${post.publishedAt as string}#${postRkey}`,
+      SK: `${new Date(Math.min(new Date(post.publishedAt as string).getTime(), Date.now())).toISOString()}#${postRkey}`,
       entityType: 'timeline-item',
       authorDid,
       rkey: postRkey,
diff --git a/infra/backfill/src/index.ts b/infra/backfill/src/index.ts
index adfdc9e..9124716 100644
--- a/infra/backfill/src/index.ts
+++ b/infra/backfill/src/index.ts
@@ -171,7 +171,7 @@ async function upsertDocument(
     PK: `u#${did}#post`,
     SK: `p#${rkey}`,
     GSI1PK: 'blog-post#published',
-    GSI1SK: `${record.publishedAt}#${rkey}`,
+    GSI1SK: `${new Date(Math.min(new Date(record.publishedAt).getTime(), Date.now())).toISOString()}#${rkey}`,
     entityType: 'blog-post',
     visibility: 'published',
     atUri: `at://${did}/site.standard.document/${rkey}`,
@@ -231,7 +231,7 @@ async function fanInExistingPosts(
     const postRkey = (post.SK as string).slice('p#'.length)
     const item: Record<string, unknown> = {
       PK: `u#${readerDid}#timeline`,
-      SK: `${post.publishedAt as string}#${postRkey}`,
+      SK: `${new Date(Math.min(new Date(post.publishedAt as string).getTime(), Date.now())).toISOString()}#${postRkey}`,
       entityType: 'timeline-item',
       authorDid,
       rkey: postRkey,
diff --git a/infra/indexer/src/index.ts b/infra/indexer/src/index.ts
index d30c843..f7f9c84 100644
--- a/infra/indexer/src/index.ts
+++ b/infra/indexer/src/index.ts
@@ -308,7 +308,7 @@ async function fanOutToTimeline(
       const readerDid = (subscriber.SK as string).slice('u#'.length)
       const item: Record<string, unknown> = {
         PK: `u#${readerDid}#timeline`,
-        SK: `${record.publishedAt}#${rkey}`,
+        SK: `${new Date(Math.min(new Date(record.publishedAt).getTime(), Date.now())).toISOString()}#${rkey}`,
         entityType: 'timeline-item',
         authorDid,
         rkey,
@@ -357,7 +357,7 @@ async function fanInExistingPosts(readerDid: string, authorDid: string, publicat
     const postRkey = (post.SK as string).slice('p#'.length)
     const item: Record<string, unknown> = {
       PK: `u#${readerDid}#timeline`,
-      SK: `${post.publishedAt as string}#${postRkey}`,
+      SK: `${new Date(Math.min(new Date(post.publishedAt as string).getTime(), Date.now())).toISOString()}#${postRkey}`,
       entityType: 'timeline-item',
       authorDid,
       rkey: postRkey,