diff --git a/src/app.ts b/src/app.ts
index c3212f8f..e637cb4f 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -23,6 +23,7 @@ import {
   accountLookupController,
   accountSearchController,
   accountStatusesController,
+  blockController,
   createAccountController,
   favouritesController,
   followController,
@@ -135,6 +136,7 @@ app.patch(
 app.get('/api/v1/accounts/search', accountSearchController);
 app.get('/api/v1/accounts/lookup', accountLookupController);
 app.get('/api/v1/accounts/relationships', relationshipsController);
+app.post('/api/v1/accounts/:pubkey{[0-9a-f]{64}}/block', blockController);
 app.post('/api/v1/accounts/:pubkey{[0-9a-f]{64}}/follow', followController);
 app.get('/api/v1/accounts/:pubkey{[0-9a-f]{64}}/followers', followersController);
 app.get('/api/v1/accounts/:pubkey{[0-9a-f]{64}}/following', followingController);
diff --git a/src/client.ts b/src/client.ts
index fbcfaa5f..511cbc75 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -52,6 +52,7 @@ function getEvents<K extends number>(filters: Filter<K>[], opts: GetEventsOpts =
 /** Publish an event to the given relays, or the entire pool. */
 function storeEvent(event: Event, opts: StoreEventOpts = {}): Promise<void> {
   const { relays = activeRelays } = opts;
+  const debug = Debug('ditto:client:publish');
   debug('EVENT', event);
   pool.publish(event, relays);
   return Promise.resolve();
diff --git a/src/controllers/api/accounts.ts b/src/controllers/api/accounts.ts
index 5609fbef..9e1acc80 100644
--- a/src/controllers/api/accounts.ts
+++ b/src/controllers/api/accounts.ts
@@ -246,6 +246,20 @@ const followingController: AppController = async (c) => {
   return c.json(accounts.filter(Boolean));
 };
 
+const blockController: AppController = async (c) => {
+  const sourcePubkey = c.get('pubkey')!;
+  const targetPubkey = c.req.param('pubkey');
+
+  await updateListEvent(
+    { kinds: [10000], authors: [sourcePubkey] },
+    (tags) => addTag(tags, ['p', targetPubkey]),
+    c,
+  );
+
+  const relationship = await renderRelationship(sourcePubkey, targetPubkey);
+  return c.json(relationship);
+};
+
 const favouritesController: AppController = async (c) => {
   const pubkey = c.get('pubkey')!;
   const params = paginationSchema.parse(c.req.query());
@@ -275,6 +289,7 @@ export {
   accountLookupController,
   accountSearchController,
   accountStatusesController,
+  blockController,
   createAccountController,
   favouritesController,
   followController,
diff --git a/src/utils/web.ts b/src/utils/web.ts
index 3687a652..1e7be076 100644
--- a/src/utils/web.ts
+++ b/src/utils/web.ts
@@ -60,7 +60,7 @@ function updateListEvent<K extends number>(
 ): Promise<Event<K>> {
   return updateEvent(filter, (prev) => ({
     kind: filter.kinds[0],
-    content: prev?.content,
+    content: prev?.content ?? '',
     tags: fn(prev?.tags ?? []),
   }), c);
 }
diff --git a/src/views/mastodon/relationships.ts b/src/views/mastodon/relationships.ts
index 97fa0f13..e5ce2807 100644
--- a/src/views/mastodon/relationships.ts
+++ b/src/views/mastodon/relationships.ts
@@ -15,7 +15,7 @@ async function renderRelationship(sourcePubkey: string, targetPubkey: string) {
     showing_reblogs: true,
     notifying: false,
     followed_by: target3 ? hasTag(target3?.tags, ['p', sourcePubkey]) : false,
-    blocking: event10000 ? hasTag(target10000.tags, ['p', targetPubkey]) : false,
+    blocking: event10000 ? hasTag(event10000.tags, ['p', targetPubkey]) : false,
     blocked_by: target10000 ? hasTag(target10000.tags, ['p', sourcePubkey]) : false,
     muting: false,
     muting_notifications: false,