diff --git a/packages/client/src/components/MkUserSelectDialog.vue b/packages/client/src/components/MkUserSelectDialog.vue
index e7407a106..485b3d890 100644
--- a/packages/client/src/components/MkUserSelectDialog.vue
+++ b/packages/client/src/components/MkUserSelectDialog.vue
@@ -96,6 +96,7 @@ import XModalWindow from "@/components/MkModalWindow.vue";
 import * as os from "@/os";
 import { defaultStore } from "@/store";
 import { i18n } from "@/i18n";
+import { toASCII } from "punycode/";
 
 const emit = defineEmits<{
 	(ev: "ok", selected: misskey.entities.UserDetailed): void;
@@ -117,7 +118,7 @@ const search = () => {
 	}
 	os.api("users/search-by-username-and-host", {
 		username: username,
-		host: host,
+		host: toASCII(host),
 		limit: 10,
 		detail: false,
 	}).then((_users) => {
diff --git a/packages/client/src/scripts/autocomplete.ts b/packages/client/src/scripts/autocomplete.ts
index 99f9dce40..2efa0249a 100644
--- a/packages/client/src/scripts/autocomplete.ts
+++ b/packages/client/src/scripts/autocomplete.ts
@@ -3,7 +3,7 @@ import getCaretCoordinates from "textarea-caret";
 import { toASCII } from "punycode/";
 import { popup } from "@/os";
 
-const mentionRegex = /@(?<user>[a-zA-Z0-9_]+|$)@?(?<host>[a-zA-Z0-9-.]+)?$/g;
+const mentionRegex = /@(?<user>[a-zA-Z0-9_]+|$)@?(?<host>[\S]+)?$/g;
 
 export class Autocomplete {
 	private suggestion: {