diff --git a/src/modules/core/index.ts b/src/modules/core/index.ts
index 8efc580..eeed825 100644
--- a/src/modules/core/index.ts
+++ b/src/modules/core/index.ts
@@ -2,11 +2,10 @@ import autobind from 'autobind-decorator';
 import Module from '../../module';
 import Message from '../../message';
 import serifs from '../../serifs';
+import { safeForInterpolate } from '../../utils/safe-for-interpolate';
 
 const titles = ['さん', 'くん', '君', 'ちゃん', '様', '先生'];
 
-const invalidChars = ['@', '#', '*', ':', '(', '[', ' ', '　'];
-
 export default class extends Module {
 	public readonly name = 'core';
 
@@ -87,7 +86,7 @@ export default class extends Module {
 			return true;
 		}
 
-		if (invalidChars.some(c => name.includes(c))) {
+		if (!safeForInterpolate(name)) {
 			msg.reply(serifs.core.invalidName);
 			return true;
 		}
diff --git a/src/utils/safe-for-interpolate.ts b/src/utils/safe-for-interpolate.ts
new file mode 100644
index 0000000..4848a3e
--- /dev/null
+++ b/src/utils/safe-for-interpolate.ts
@@ -0,0 +1,16 @@
+const invalidChars = [
+	'@',
+	'#',
+	'*',
+	':',
+	'(',
+	')',
+	'[',
+	']',
+	' ',
+	'　',
+];
+
+export function safeForInterpolate(text: string): boolean {
+	return !invalidChars.some(c => text.includes(c));
+}