diff --git a/entrypoint.example.ts b/entrypoint.example.ts
index 61fe279..57c3087 100644
--- a/entrypoint.example.ts
+++ b/entrypoint.example.ts
@@ -9,6 +9,7 @@ import {
   pubkeyBanPolicy,
   rateLimitPolicy,
   readStdin,
+  regexPolicy,
   writeStdout,
 } from './mod.ts';
 
@@ -20,6 +21,7 @@ for await (const msg of readStdin()) {
     [rateLimitPolicy, { whitelist: ['127.0.0.1'] }],
     [pubkeyBanPolicy, ['e810fafa1e89cdf80cced8e013938e87e21b699b24c8570537be92aec4b12c18']],
     [keywordPolicy, ['https://t.me/']],
+    [regexPolicy, /(🟠|🔥|😳)ChtaGPT/i],
   ]);
 
   writeStdout(result);
diff --git a/mod.ts b/mod.ts
index b5f080f..cf5f336 100644
--- a/mod.ts
+++ b/mod.ts
@@ -5,6 +5,7 @@ export { default as noopPolicy } from './src/policies/noop-policy.ts';
 export { default as pubkeyBanPolicy } from './src/policies/pubkey-ban-policy.ts';
 export { default as rateLimitPolicy } from './src/policies/rate-limit-policy.ts';
 export { default as readOnlyPolicy } from './src/policies/read-only-policy.ts';
+export { default as regexPolicy } from './src/policies/regex-policy.ts';
 export { default as whitelistPolicy } from './src/policies/whitelist-policy.ts';
 
 export { readStdin, writeStdout } from './src/io.ts';
diff --git a/src/policies/hellthread-policy.test.ts b/src/policies/hellthread-policy.test.ts
index b350e78..7b440f1 100644
--- a/src/policies/hellthread-policy.test.ts
+++ b/src/policies/hellthread-policy.test.ts
@@ -1,4 +1,4 @@
-import { assert } from '../deps.ts';
+import { assertEquals } from '../deps.ts';
 import { buildEvent, buildInputMessage } from '../test.ts';
 
 import hellthreadPolicy from './hellthread-policy.ts';
@@ -9,6 +9,6 @@ Deno.test('blocks events with too many mentioned users', async () => {
   const msg0 = buildInputMessage();
   const msg1 = buildInputMessage({ event: buildEvent({ tags }) });
 
-  assert((await hellthreadPolicy(msg0, { limit: 1 })).action === 'accept');
-  assert((await hellthreadPolicy(msg1, { limit: 1 })).action === 'reject');
+  assertEquals((await hellthreadPolicy(msg0, { limit: 1 })).action, 'accept');
+  assertEquals((await hellthreadPolicy(msg1, { limit: 1 })).action, 'reject');
 });
diff --git a/src/policies/keyword-policy.test.ts b/src/policies/keyword-policy.test.ts
index f33f7df..c134d02 100644
--- a/src/policies/keyword-policy.test.ts
+++ b/src/policies/keyword-policy.test.ts
@@ -1,4 +1,4 @@
-import { assert } from '../deps.ts';
+import { assertEquals } from '../deps.ts';
 import { buildEvent, buildInputMessage } from '../test.ts';
 
 import keywordPolicy from './keyword-policy.ts';
@@ -9,7 +9,7 @@ Deno.test('blocks banned pubkeys', async () => {
   const msg0 = buildInputMessage();
   const msg1 = buildInputMessage({ event: buildEvent({ content: '🔥🔥🔥 https://t.me/spam 我想死' }) });
 
-  assert((await keywordPolicy(msg0, words)).action === 'accept');
-  assert((await keywordPolicy(msg1, words)).action === 'reject');
-  assert((await keywordPolicy(msg1, [])).action === 'accept');
+  assertEquals((await keywordPolicy(msg0, words)).action, 'accept');
+  assertEquals((await keywordPolicy(msg1, words)).action, 'reject');
+  assertEquals((await keywordPolicy(msg1, [])).action, 'accept');
 });
diff --git a/src/policies/noop-policy.test.ts b/src/policies/noop-policy.test.ts
index 577ee51..a22456a 100644
--- a/src/policies/noop-policy.test.ts
+++ b/src/policies/noop-policy.test.ts
@@ -1,9 +1,9 @@
-import { assert } from '../deps.ts';
+import { assertEquals } from '../deps.ts';
 import { buildInputMessage } from '../test.ts';
 
 import noopPolicy from './noop-policy.ts';
 
 Deno.test('allows events', async () => {
   const msg = buildInputMessage();
-  assert((await noopPolicy(msg)).action === 'accept');
+  assertEquals((await noopPolicy(msg)).action, 'accept');
 });
diff --git a/src/policies/pubkey-ban-policy.test.ts b/src/policies/pubkey-ban-policy.test.ts
index 6cd04c8..d86a14e 100644
--- a/src/policies/pubkey-ban-policy.test.ts
+++ b/src/policies/pubkey-ban-policy.test.ts
@@ -1,4 +1,4 @@
-import { assert } from '../deps.ts';
+import { assertEquals } from '../deps.ts';
 import { buildEvent, buildInputMessage } from '../test.ts';
 
 import pubkeyBanPolicy from './pubkey-ban-policy.ts';
@@ -8,8 +8,8 @@ Deno.test('blocks banned pubkeys', async () => {
   const msgB = buildInputMessage({ event: buildEvent({ pubkey: 'B' }) });
   const msgC = buildInputMessage({ event: buildEvent({ pubkey: 'C' }) });
 
-  assert((await pubkeyBanPolicy(msgA, [])).action === 'accept');
-  assert((await pubkeyBanPolicy(msgA, ['A'])).action === 'reject');
-  assert((await pubkeyBanPolicy(msgC, ['B', 'A'])).action === 'accept');
-  assert((await pubkeyBanPolicy(msgB, ['B', 'A'])).action === 'reject');
+  assertEquals((await pubkeyBanPolicy(msgA, [])).action, 'accept');
+  assertEquals((await pubkeyBanPolicy(msgA, ['A'])).action, 'reject');
+  assertEquals((await pubkeyBanPolicy(msgC, ['B', 'A'])).action, 'accept');
+  assertEquals((await pubkeyBanPolicy(msgB, ['B', 'A'])).action, 'reject');
 });
diff --git a/src/policies/read-only-policy.test.ts b/src/policies/read-only-policy.test.ts
index 3da9cc0..93aeadb 100644
--- a/src/policies/read-only-policy.test.ts
+++ b/src/policies/read-only-policy.test.ts
@@ -1,4 +1,4 @@
-import { assert } from '../deps.ts';
+import { assertEquals } from '../deps.ts';
 import { buildInputMessage } from '../test.ts';
 
 import readOnlyPolicy from './read-only-policy.ts';
@@ -6,5 +6,5 @@ import readOnlyPolicy from './read-only-policy.ts';
 Deno.test('always rejects', async () => {
   const msg = buildInputMessage();
   const result = await readOnlyPolicy(msg);
-  assert(result.action === 'reject');
+  assertEquals(result.action, 'reject');
 });
diff --git a/src/policies/regex-policy.test.ts b/src/policies/regex-policy.test.ts
new file mode 100644
index 0000000..400a984
--- /dev/null
+++ b/src/policies/regex-policy.test.ts
@@ -0,0 +1,15 @@
+import { assertEquals } from '../deps.ts';
+import { buildEvent, buildInputMessage } from '../test.ts';
+
+import regexPolicy from './regex-policy.ts';
+
+Deno.test('blocks banned regular expressions', async () => {
+  const msg = buildInputMessage({ event: buildEvent({ content: '🔥🔥🔥 https://t.me/spam 我想死' }) });
+
+  assertEquals((await regexPolicy(msg)).action, 'accept');
+  assertEquals((await regexPolicy(msg, /https:\/\/t\.me\/\w+/i)).action, 'reject');
+  assertEquals((await regexPolicy(msg, /🔥{1,3}/)).action, 'reject');
+  assertEquals((await regexPolicy(msg, /🔥{4}/)).action, 'accept');
+  assertEquals((await regexPolicy(msg, /🔥$/)).action, 'accept');
+  assertEquals((await regexPolicy(msg, /^🔥/)).action, 'reject');
+});
diff --git a/src/policies/regex-policy.ts b/src/policies/regex-policy.ts
new file mode 100644
index 0000000..e51da4e
--- /dev/null
+++ b/src/policies/regex-policy.ts
@@ -0,0 +1,22 @@
+import { Policy } from '../types.ts';
+
+/** Reject events whose content matches the regex. */
+const regexPolicy: Policy<RegExp> = ({ event: { id, content } }, regex) => {
+  const isMatch = regex ? regex.test(content) : false;
+
+  if (isMatch) {
+    return {
+      id,
+      action: 'reject',
+      msg: 'Event matches a banned expression.',
+    };
+  }
+
+  return {
+    id,
+    action: 'accept',
+    msg: '',
+  };
+};
+
+export default regexPolicy;
diff --git a/src/policies/whitelist-policy.test.ts b/src/policies/whitelist-policy.test.ts
index e6afe32..881fdef 100644
--- a/src/policies/whitelist-policy.test.ts
+++ b/src/policies/whitelist-policy.test.ts
@@ -1,4 +1,4 @@
-import { assert } from '../deps.ts';
+import { assertEquals } from '../deps.ts';
 import { buildEvent, buildInputMessage } from '../test.ts';
 
 import whitelistPolicy from './whitelist-policy.ts';
@@ -8,8 +8,8 @@ Deno.test('allows only whitelisted pubkeys', async () => {
   const msgB = buildInputMessage({ event: buildEvent({ pubkey: 'B' }) });
   const msgC = buildInputMessage({ event: buildEvent({ pubkey: 'C' }) });
 
-  assert((await whitelistPolicy(msgA, [])).action === 'reject');
-  assert((await whitelistPolicy(msgA, ['A'])).action === 'accept');
-  assert((await whitelistPolicy(msgC, ['B', 'A'])).action === 'reject');
-  assert((await whitelistPolicy(msgB, ['B', 'A'])).action === 'accept');
+  assertEquals((await whitelistPolicy(msgA, [])).action, 'reject');
+  assertEquals((await whitelistPolicy(msgA, ['A'])).action, 'accept');
+  assertEquals((await whitelistPolicy(msgC, ['B', 'A'])).action, 'reject');
+  assertEquals((await whitelistPolicy(msgB, ['B', 'A'])).action, 'accept');
 });