diff --git a/filter.ts b/filter.ts
index 1da520f..f28e9b9 100644
--- a/filter.ts
+++ b/filter.ts
@@ -12,8 +12,8 @@ export type Filter<K extends number = Kind> = {
 }
 
 export function matchFilter(
-  filter: Filter,
-  event: Event
+  filter: Filter<number>,
+  event: Event<number>
 ): boolean {
   if (filter.ids && filter.ids.indexOf(event.id) === -1) {
     if (!filter.ids.some(prefix => event.id.startsWith(prefix))) {
@@ -48,8 +48,8 @@ export function matchFilter(
 }
 
 export function matchFilters(
-  filters: Filter[],
-  event: Event
+  filters: Filter<number>[],
+  event: Event<number>
 ): boolean {
   for (let i = 0; i < filters.length; i++) {
     if (matchFilter(filters[i], event)) return true