diff --git a/util.ts b/util.ts
index fe979bd..5ffc571 100644
--- a/util.ts
+++ b/util.ts
@@ -23,4 +23,4 @@ export const error = (error: string) => ({ error });
 export const ok = { result: null };
 
 // deno-lint-ignore no-explicit-any
-export const isKnownError = (e: any): e is T.KnownError => e.error || e["error-code"]
\ No newline at end of file
+export const isKnownError = (e: unknown): e is T.KnownError => e instanceof Object &&  ('error' in e || "error-code" in e)
\ No newline at end of file