diff --git a/denops/dpp/app.ts b/denops/dpp/app.ts
index 6ea6a90..2fc4783 100644
--- a/denops/dpp/app.ts
+++ b/denops/dpp/app.ts
@@ -15,8 +15,8 @@ export function main(denops: Denops) {
       arg2: unknown,
       arg3: unknown,
     ): Promise<unknown | undefined> {
-      const extName = ensure(arg1, is.String);
-      const actionName = ensure(arg2, is.String);
+      const extName = ensure(arg1, is.String) as string;
+      const actionName = ensure(arg2, is.String) as string;
       const actionParams = ensure(arg3, is.Record);
 
       // Set current options from dpp#_options
@@ -43,9 +43,9 @@ export function main(denops: Denops) {
       arg3: unknown,
     ): Promise<void> {
       //const startTime = Date.now();
-      const basePath = ensure(arg1, is.String);
-      const configPath = ensure(arg2, is.String);
-      const name = ensure(arg3, is.String);
+      const basePath = ensure(arg1, is.String) as string;
+      const configPath = ensure(arg2, is.String) as string;
+      const name = ensure(arg3, is.String) as string;
 
       // NOTE: Import module with fragment so that reload works properly.
       // https://github.com/vim-denops/denops.vim/issues/227
diff --git a/denops/dpp/deps.ts b/denops/dpp/deps.ts
index 8eb5953..23b4456 100644
--- a/denops/dpp/deps.ts
+++ b/denops/dpp/deps.ts
@@ -16,7 +16,7 @@ export {
   assertEquals,
   assertInstanceOf,
   equal,
-} from "https://deno.land/std@0.220.1/assert/mod.ts";
+} from "https://deno.land/std@0.221.0/assert/mod.ts";
 export {
   basename,
   dirname,
@@ -25,10 +25,10 @@ export {
   parse,
   SEPARATOR as pathsep,
   toFileUrl,
-} from "https://deno.land/std@0.220.1/path/mod.ts";
+} from "https://deno.land/std@0.221.0/path/mod.ts";
 export {
   deadline,
   DeadlineError,
-} from "https://deno.land/std@0.220.1/async/mod.ts";
+} from "https://deno.land/std@0.221.0/async/mod.ts";
 export { TimeoutError } from "https://deno.land/x/msgpack_rpc@v4.0.1/response_waiter.ts";
 export { Lock } from "https://deno.land/x/async@v2.1.0/mod.ts";