diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
index 5b53db1..68472b3 100644
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@@ -27,5 +27,6 @@ jobs:
         node-version: ${{ matrix.node-version }}
         cache: 'npm'
     - run: npm ci
+    - run: npm run type-check
     - run: npm run build --if-present
     - run: npm test -- --testTimeout 5000
diff --git a/author.ts b/author.ts
index cc35add..9bae243 100644
--- a/author.ts
+++ b/author.ts
@@ -1,5 +1,5 @@
 import type {OnEvent, OnEventObject, RelayPool} from "./relay-pool";
-import {Filter, Kind} from "nostr-tools";
+import {type Filter, Kind} from "nostr-tools";
 import type {EventObject} from "./event";
 
 export class Author {
diff --git a/collect.ts b/collect.ts
index 0a96348..8c16030 100644
--- a/collect.ts
+++ b/collect.ts
@@ -1,5 +1,5 @@
-import {Event} from "nostr-tools";
-import {OnEvent} from "./on-event-filters";
+import type {Event} from "nostr-tools";
+import type {OnEvent} from "./on-event-filters";
 
 const binarySearch = function (a: Event[], target: Event) {
   var l = 0,
diff --git a/event-cache-test.ts b/event-cache-test.ts
index 626897b..da0aa8a 100644
--- a/event-cache-test.ts
+++ b/event-cache-test.ts
@@ -1,6 +1,6 @@
 /* eslint-env jest */
 
-import {Kind, Event} from "nostr-tools";
+import {Kind, type Event} from "nostr-tools";
 import {EventCache} from "./event-cache";
 
 describe("EventCache", () => {
diff --git a/event-cache.ts b/event-cache.ts
index c5d67a8..511e31e 100644
--- a/event-cache.ts
+++ b/event-cache.ts
@@ -1,4 +1,4 @@
-import {Filter, Kind, Event} from "nostr-tools";
+import {type Filter, Kind, type Event} from "nostr-tools";
 
 export class EventCache {
   eventsById: Map<string, Event> = new Map();
diff --git a/event-demultiplexer-test.ts b/event-demultiplexer-test.ts
index 82c9665..f8642c8 100644
--- a/event-demultiplexer-test.ts
+++ b/event-demultiplexer-test.ts
@@ -1,6 +1,6 @@
 /* eslint-env jest */
 
-import {Filter, matchFilter, Event, UnsignedEvent} from "nostr-tools";
+import {type Filter, matchFilter, type Event, type UnsignedEvent} from "nostr-tools";
 import {EventDemultiplexer} from "./event-demultiplexer";
 
 let eventFrom = (event: UnsignedEvent & {id: string}) => {
diff --git a/event-demultiplexer.ts b/event-demultiplexer.ts
index 9afd99e..1d5b6f5 100644
--- a/event-demultiplexer.ts
+++ b/event-demultiplexer.ts
@@ -1,5 +1,5 @@
-import {Filter, matchFilter, Event} from "nostr-tools";
-import {OnEvent} from "./on-event-filters";
+import {type Filter, matchFilter, type Event} from "nostr-tools";
+import type {OnEvent} from "./on-event-filters";
 
 export class EventDemultiplexer {
   filterAndOnEventByEvent: Map<string, [Filter, OnEvent][]> = new Map();
diff --git a/event-persister.ts b/event-persister.ts
index 2272ac3..94feed8 100644
--- a/event-persister.ts
+++ b/event-persister.ts
@@ -36,3 +36,6 @@
 //     }
 //   }
 // }
+
+// Needed for isolatedModules to not complain
+export const __unused = true;
diff --git a/event.ts b/event.ts
index 9b608d7..0723206 100644
--- a/event.ts
+++ b/event.ts
@@ -1,6 +1,6 @@
-import {Kind, Event} from "nostr-tools";
+import type {Kind, Event} from "nostr-tools";
 import {Author} from "./author";
-import {RelayPool} from "./relay-pool";
+import type {RelayPool} from "./relay-pool";
 
 import type {OnEvent} from "./on-event-filters";
 export class EventObject implements Event {
diff --git a/group-filters-by-relay.ts b/group-filters-by-relay.ts
index dcbb709..35a06be 100644
--- a/group-filters-by-relay.ts
+++ b/group-filters-by-relay.ts
@@ -1,4 +1,4 @@
-import {Filter, Event} from "nostr-tools";
+import type {Filter, Event} from "nostr-tools";
 import {mergeSimilarAndRemoveEmptyFilters} from "./merge-similar-filters";
 import {
   doNotEmitDuplicateEvents,
@@ -6,8 +6,8 @@ import {
   matchOnEventFilters,
   type OnEvent,
 } from "./on-event-filters";
-import {EventCache} from "./event-cache";
-import {FilterToSubscribe} from "./relay-pool";
+import type {EventCache} from "./event-cache";
+import type {FilterToSubscribe} from "./relay-pool";
 import {CallbackReplayer} from "./callback-replayer";
 
 const unique = (arr: string[]) => [...new Set(arr)];
diff --git a/in-memory-relay-server.ts b/in-memory-relay-server.ts
index a6ea5cf..cf61126 100644
--- a/in-memory-relay-server.ts
+++ b/in-memory-relay-server.ts
@@ -1,4 +1,4 @@
-import {Event, Filter, matchFilters} from "nostr-tools";
+import {type Event, type Filter, matchFilters} from "nostr-tools";
 import {WebSocket, WebSocketServer} from "isomorphic-ws";
 
 const _ = WebSocket; // Importing WebSocket is needed for WebSocketServer to work
diff --git a/metadata-cache.ts b/metadata-cache.ts
index 8a9a4b5..11495f4 100644
--- a/metadata-cache.ts
+++ b/metadata-cache.ts
@@ -1,4 +1,4 @@
-import {Event} from "nostr-tools";
+import type {Event} from "nostr-tools";
 
 export class MetadataCache {
   data: Map<string, Event>;
diff --git a/newest-event-cache.ts b/newest-event-cache.ts
index f800b56..00eeebd 100644
--- a/newest-event-cache.ts
+++ b/newest-event-cache.ts
@@ -1,5 +1,5 @@
-import {Event, Filter} from "nostr-tools";
-import {RelayPool} from "./relay-pool";
+import type {Event, Filter} from "nostr-tools";
+import type {RelayPool} from "./relay-pool";
 
 export class NewestEventCache {
   data: Map<string, Event>;
diff --git a/on-event-filters.ts b/on-event-filters.ts
index 97b6f1d..85770e3 100644
--- a/on-event-filters.ts
+++ b/on-event-filters.ts
@@ -1,5 +1,5 @@
-import {Filter, Kind, matchFilter, Event} from "nostr-tools";
-import {EventObject} from "./event";
+import {type Filter, Kind, matchFilter, type Event} from "nostr-tools";
+import type {EventObject} from "./event";
 export type OnEventArgs = [
   event: Event,
   afterEose: boolean,
diff --git a/package.json b/package.json
index faffcc0..6e7b83a 100644
--- a/package.json
+++ b/package.json
@@ -62,6 +62,7 @@
     "build": "node build.js",
     "pretest": "node build.js",
     "test": "NODE_OPTIONS=--experimental-vm-modules npx jest",
-    "publish": "npm i && npm run build && npm run test -- --testTimeout 5000 && npm publish"
+    "publish": "npm i && npm run build && npm run test -- --testTimeout 5000 && npm publish",
+    "type-check": "tsc"
   }
 }
diff --git a/relay-pool-worker.ts b/relay-pool-worker.ts
index c2a793d..cc59f95 100644
--- a/relay-pool-worker.ts
+++ b/relay-pool-worker.ts
@@ -1,5 +1,5 @@
 import type {Event} from "nostr-tools";
-import {OnEose, OnEvent, SubscriptionOptions} from "./relay-pool";
+import type {OnEose, OnEvent, SubscriptionOptions} from "./relay-pool";
 
 export class RelayPoolWorker {
   // eslint-disable-next-line no-undef
diff --git a/relay-pool.test.ts b/relay-pool.test.ts
index d4af9b4..6412c55 100644
--- a/relay-pool.test.ts
+++ b/relay-pool.test.ts
@@ -5,7 +5,7 @@ import {
   generatePrivateKey,
   getEventHash,
   getPublicKey,
-  Event,
+  type Event,
 } from "nostr-tools";
 import {RelayPool} from "./relay-pool";
 import {InMemoryRelayServer} from "./in-memory-relay-server";
diff --git a/relay-pool.ts b/relay-pool.ts
index 9a59a3e..e4cc236 100644
--- a/relay-pool.ts
+++ b/relay-pool.ts
@@ -1,14 +1,14 @@
-import {Filter, Event} from "nostr-tools";
+import type {Filter, Event} from "nostr-tools";
 import {mergeSimilarAndRemoveEmptyFilters} from "./merge-similar-filters";
-import {type Relay, relayInit, Sub} from "./relay";
-import {OnEventObject, type OnEvent} from "./on-event-filters";
+import {type Relay, relayInit, type Sub} from "./relay";
+import type {OnEventObject, OnEvent} from "./on-event-filters";
 import {EventCache} from "./event-cache";
 import {EventObject} from "./event";
 import {
   batchFiltersByRelay,
   groupFiltersByRelayAndEmitCacheHits,
 } from "./group-filters-by-relay";
-import {CallbackReplayer} from "./callback-replayer";
+import type {CallbackReplayer} from "./callback-replayer";
 import {NewestEventCache} from "./newest-event-cache";
 
 const unique = (arr: string[]) => [...new Set(arr)];
diff --git a/relay-pool.worker.ts b/relay-pool.worker.ts
index e716e56..6c2707a 100644
--- a/relay-pool.worker.ts
+++ b/relay-pool.worker.ts
@@ -1,6 +1,6 @@
 /* eslint-disable no-undef */
 // worker.ts
-import {RelayPool, SubscriptionOptions} from "./relay-pool";
+import {RelayPool, type SubscriptionOptions} from "./relay-pool";
 import type {Event} from "nostr-tools";
 
 let relayPool: RelayPool;
diff --git a/tsconfig.json b/tsconfig.json
index 5220cba..5acd24f 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -9,6 +9,9 @@
     "esModuleInterop": true,
     "skipLibCheck": true,
     "emitDeclarationOnly": true,
+    "importsNotUsedAsValues": "error",
+    "preserveValueImports": true,
+    "isolatedModules": true,
     "outDir": "dist",
     "rootDir": ".",
   }