diff --git a/src/plugins/discourse/__snapshots__/fetch.test.js.snap b/src/plugins/discourse/__snapshots__/fetch.test.js.snap
index dfbe108..62945be 100644
--- a/src/plugins/discourse/__snapshots__/fetch.test.js.snap
+++ b/src/plugins/discourse/__snapshots__/fetch.test.js.snap
@@ -47,6 +47,7 @@ Object {
   ],
   "topic": Object {
     "authorUsername": "d11",
+    "categoryId": 1,
     "id": 11,
     "timestampMs": 1564744349408,
     "title": "My First Test Post",
diff --git a/src/plugins/discourse/createGraph.test.js b/src/plugins/discourse/createGraph.test.js
index 213b777..4a4423b 100644
--- a/src/plugins/discourse/createGraph.test.js
+++ b/src/plugins/discourse/createGraph.test.js
@@ -84,6 +84,8 @@ describe("plugins/discourse/createGraph", () => {
       title: "first topic",
       timestampMs: 0,
       authorUsername: "decentralion",
+      categoryId: 1,
+      bumpedMs: 0,
     };
     const post1 = {
       id: 1,
diff --git a/src/plugins/discourse/fetch.js b/src/plugins/discourse/fetch.js
index 6ac6969..ccb7ab9 100644
--- a/src/plugins/discourse/fetch.js
+++ b/src/plugins/discourse/fetch.js
@@ -20,13 +20,29 @@ export type PostId = number;
 export type TopicId = number;
 export type CategoryId = number;
 
-export type Topic = {|
+/**
+ * The "view" received from the Discourse API
+ * when getting a topic by ID.
+ *
+ * This filters some relevant data like bumpedMs,
+ * and the type separation makes this distinction clear.
+ */
+export type TopicView = {|
   +id: TopicId,
+  +categoryId: CategoryId,
   +title: string,
   +timestampMs: number,
   +authorUsername: string,
 |};
 
+/**
+ * A complete Topic object.
+ */
+export type Topic = {|
+  ...TopicView,
+  +bumpedMs: number,
+|};
+
 export type Post = {|
   +id: PostId,
   +topicId: TopicId,
@@ -43,7 +59,7 @@ export type Post = {|
 |};
 
 export type TopicWithPosts = {|
-  +topic: Topic,
+  +topic: TopicView,
   // Not guaranteed to contain all the Posts in the topic—clients will need to
   // manually request some posts. The raw response actually includes a list of
   // all the PostIds in the topic, but for now we don't use them.
@@ -182,11 +198,12 @@ export class Fetcher implements Discourse {
     }
     failForNotOk(response);
     const json = await response.json();
-    const posts = json.post_stream.posts.map(parsePost);
-    const topic: Topic = {
+    let posts = json.post_stream.posts.map(parsePost);
+    const topic: TopicView = {
       id: json.id,
+      categoryId: json.category_id,
       title: json.title,
-      timestampMs: +new Date(json.created_at),
+      timestampMs: Date.parse(json.created_at),
       authorUsername: json.details.created_by.username,
     };
     return {topic, posts};
diff --git a/src/plugins/discourse/mirror.js b/src/plugins/discourse/mirror.js
index 663e4c8..d5ff83a 100644
--- a/src/plugins/discourse/mirror.js
+++ b/src/plugins/discourse/mirror.js
@@ -1,7 +1,7 @@
 // @flow
 
 import type {TaskReporter} from "../../util/taskReporter";
-import type {Discourse, CategoryId} from "./fetch";
+import type {Discourse, CategoryId, Topic} from "./fetch";
 import {MirrorRepository} from "./mirrorRepository";
 
 export type MirrorOptions = {|
@@ -117,7 +117,10 @@ export class Mirror {
       const topicWithPosts = await this._fetcher.topicWithPosts(topicId);
       if (topicWithPosts != null) {
         const {topic, posts} = topicWithPosts;
-        this._repo.addTopic(topic);
+        // TODO: Quick hack, as TopicView does not include bumpedMs.
+        // This should be resolved in the new sync logic.
+        const workaroundTopic: Topic = {...topic, bumpedMs: topic.timestampMs};
+        this._repo.addTopic(workaroundTopic);
         for (const post of posts) {
           addPost(post);
         }
diff --git a/src/plugins/discourse/mirror.test.js b/src/plugins/discourse/mirror.test.js
index 64c2d0d..314253c 100644
--- a/src/plugins/discourse/mirror.test.js
+++ b/src/plugins/discourse/mirror.test.js
@@ -9,6 +9,7 @@ import {
   type TopicId,
   type PostId,
   type Topic,
+  type TopicView,
   type Post,
   type TopicWithPosts,
   type LikeAction,
@@ -64,7 +65,7 @@ class MockFetcher implements Discourse {
     // Only return the first post in the posts array, to ensure that we have to
     // test the functionality where we manually grab posts by ID
     const posts = [firstPost];
-    return {topic: this._topic(id), posts};
+    return {topic: this._topicView(id), posts};
   }
 
   async likesByUser(
@@ -79,8 +80,16 @@ class MockFetcher implements Discourse {
   }
 
   _topic(id: TopicId): Topic {
+    return {
+      ...this._topicView(id),
+      bumpedMs: 1000,
+    };
+  }
+
+  _topicView(id: TopicId): TopicView {
     return {
       id,
+      categoryId: 1,
       title: `topic ${id}`,
       timestampMs: 1000,
       authorUsername: "credbot",
diff --git a/src/plugins/discourse/mirrorRepository.js b/src/plugins/discourse/mirrorRepository.js
index bc02c54..3aac391 100644
--- a/src/plugins/discourse/mirrorRepository.js
+++ b/src/plugins/discourse/mirrorRepository.js
@@ -3,17 +3,11 @@
 import type {Database} from "better-sqlite3";
 import stringify from "json-stable-stringify";
 import dedent from "../../util/dedent";
-import {
-  type TopicId,
-  type PostId,
-  type Topic,
-  type Post,
-  type LikeAction,
-} from "./fetch";
+import type {TopicId, PostId, Topic, Post, LikeAction} from "./fetch";
 
 // The version should be bumped any time the database schema is changed,
 // so that the cache will be properly invalidated.
-const VERSION = "discourse_mirror_v4";
+const VERSION = "discourse_mirror_v5";
 
 /**
  * An interface for reading the local Discourse data.
@@ -142,8 +136,10 @@ export class SqliteMirrorRepository
       dedent`\
         CREATE TABLE topics (
             id INTEGER PRIMARY KEY,
+            category_id INTEGER NOT NULL,
             title TEXT NOT NULL,
             timestamp_ms INTEGER NOT NULL,
+            bumped_ms INTEGER NOT NULL,
             author_username TEXT NOT NULL,
             FOREIGN KEY(author_username) REFERENCES users(username)
         )
@@ -198,17 +194,21 @@ export class SqliteMirrorRepository
         dedent`\
         SELECT
           id,
+          category_id,
+          title,
           timestamp_ms,
-          author_username,
-          title
+          bumped_ms,
+          author_username
         FROM topics`
       )
       .all()
       .map((x) => ({
         id: x.id,
-        timestampMs: x.timestamp_ms,
-        authorUsername: x.author_username,
+        categoryId: x.category_id,
         title: x.title,
+        timestampMs: x.timestamp_ms,
+        bumpedMs: x.bumped_ms,
+        authorUsername: x.author_username,
       }));
   }
 
@@ -336,21 +336,27 @@ export class SqliteMirrorRepository
         dedent`\
           REPLACE INTO topics (
               id,
+              category_id,
               title,
               timestamp_ms,
+              bumped_ms,
               author_username
           ) VALUES (
               :id,
+              :category_id,
               :title,
               :timestamp_ms,
+              :bumped_ms,
               :author_username
           )
         `
       )
       .run({
         id: topic.id,
+        category_id: topic.categoryId,
         title: topic.title,
         timestamp_ms: topic.timestampMs,
+        bumped_ms: topic.bumpedMs,
         author_username: topic.authorUsername,
       });
     return toAddResult(res);