diff --git a/src/collection.ts b/src/collection.ts
index 7b24f85..1cf4176 100644
--- a/src/collection.ts
+++ b/src/collection.ts
@@ -1,6 +1,6 @@
 import { UpdateOptions } from "mingo/core";
 import { UpdateExpression } from "mingo/updater";
-import { Observable, Subscription } from "rxjs";
+import { Observable, Subject, Subscription } from "rxjs";
 
 import { observe, observeOne } from "./observe/mod.ts";
 import {
@@ -26,7 +26,10 @@ export class Collection<TSchema extends Document = Document> {
     readonly storage: Storage<TSchema>,
   ) {}
 
-  get observable() {
+  get observable(): {
+    change: Subject<ChangeEvent<TSchema>>;
+    flush: Subject<void>;
+  } {
     return this.storage.observable;
   }
 
diff --git a/src/logger.ts b/src/logger.ts
index 74998ed..24b6d9f 100644
--- a/src/logger.ts
+++ b/src/logger.ts
@@ -1,5 +1,5 @@
 class Performance {
-  startedAt = performance.now();
+  startedAt: number = performance.now();
   endedAt?: number;
   duration?: number;
 
@@ -10,7 +10,7 @@ class Performance {
 }
 
 abstract class LogEvent {
-  readonly performance = new Performance();
+  readonly performance: Performance = new Performance();
 
   data?: Record<string, any>;
 
diff --git a/src/storage/storage.ts b/src/storage/storage.ts
index 15a9ad1..dec0f39 100644
--- a/src/storage/storage.ts
+++ b/src/storage/storage.ts
@@ -10,7 +10,10 @@ import { RemoveResult } from "./operators/remove.ts";
 import { UpdateResult } from "./operators/update.ts";
 
 export abstract class Storage<TSchema extends Document = Document> {
-  readonly observable = {
+  readonly observable: {
+    change: Subject<ChangeEvent<TSchema>>;
+    flush: Subject<void>;
+  } = {
     change: new Subject<ChangeEvent<TSchema>>(),
     flush: new Subject<void>(),
   };
@@ -21,7 +24,7 @@ export abstract class Storage<TSchema extends Document = Document> {
 
   constructor(
     readonly name: string,
-    readonly id = crypto.randomUUID(),
+    readonly id: string = crypto.randomUUID(),
   ) {
     this.#channel = new BroadcastChannel(`valkyr:db:${name}`);
     this.#channel.onmessage = ({ data }: MessageEvent<StorageBroadcast<TSchema>>) => {