diff --git a/frontend/src/hooks/useConversationMessages.ts b/frontend/src/hooks/useConversationMessages.ts
index f3e3f0f..aac3fbe 100644
--- a/frontend/src/hooks/useConversationMessages.ts
+++ b/frontend/src/hooks/useConversationMessages.ts
@@ -127,8 +127,13 @@ export function useConversationMessages(
     )
       return;
 
-    // Get the oldest message as cursor for the next page
-    const oldestMessage = messages[messages.length - 1];
+    // Get the true oldest message as cursor for the next page
+    const oldestMessage = messages.reduce((oldest, msg) => {
+      if (!oldest) return msg;
+      if (msg.received_at < oldest.received_at) return msg;
+      if (msg.received_at === oldest.received_at && msg.id < oldest.id) return msg;
+      return oldest;
+    }, null as Message | null);
     if (!oldestMessage) return;
 
     setLoadingOlder(true);