diff --git a/index.d.ts b/index.d.ts
index b91da40..cc82789 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -15,7 +15,7 @@ type WidgetCallback = () => Promise<string>
 
 interface MCEvent {
   readonly name?: string
-  readonly payload: unknown
+  readonly payload: Record<string, unknown | undefined>
   client: Client
   readonly type: string
 }
@@ -54,15 +54,15 @@ interface Manager {
     type: ClientEventType,
     callback: MCEventListener
   ): boolean | undefined
-  get(key: string): Promise<unknown>
-  set(key: string, value: any): Promise<boolean>
+  get(key: string): Promise<string | null>
+  set(key: string, value: string): Promise<boolean>
   route(
     path: string,
     callback: (request: Request | any) => Promise<Response> | Response
   ): string | undefined
   proxy(path: string, target: string): string | undefined
   serve(path: string, target: string): string | undefined
-  useCache(key: string, callback: Function, expiry?: number): Promise<unknown>
+  useCache(key: string, callback: Function, expiry?: number): Promise<string>
   invalidateCache(key: string): Promise<void>
   registerEmbed(name: string, callback: EmbedCallback): boolean | undefined
   registerWidget(callback: WidgetCallback): boolean | undefined
diff --git a/tests/demoComponent.ts b/tests/demoComponent.ts
index 5be8206..6043a7f 100644
--- a/tests/demoComponent.ts
+++ b/tests/demoComponent.ts
@@ -33,6 +33,9 @@ export default async function (manager: Manager, settings: ComponentSettings) {
     // Save mouse coordinates as a cookie
     const { client, payload } = event
     console.info('🐁 ⬇️ Mousedown payload:', payload)
+    if (!Array.isArray(payload.mousedown)) {
+      throw new Error('expected mousedown to be an array')
+    }
     const [firstClick] = payload.mousedown
     client.set('lastClickX', firstClick.clientX)
     client.set('lastClickY', firstClick.clientY)
@@ -85,7 +88,9 @@ export default async function (manager: Manager, settings: ComponentSettings) {
     payload.user_id = client.get('user_id')
 
     if (Object.keys(payload || {}).length) {
-      const params = new URLSearchParams(payload).toString()
+      const params = new URLSearchParams(
+        payload as Record<string, string>
+      ).toString()
       fetch(`http://www.example.com/?${params}`)
     }
   })
@@ -129,6 +134,9 @@ export default async function (manager: Manager, settings: ComponentSettings) {
           console.error('error fetching weather for embed:', error)
         }
       })
+      if (typeof embed !== 'string') {
+        throw new Error('Unexpected embed return type: ' + typeof embed)
+      }
       return embed
     }
   )