diff --git a/src/config.test.ts b/src/config.test.ts
new file mode 100644
index 000000000..a1d47164d
--- /dev/null
+++ b/src/config.test.ts
@@ -0,0 +1,19 @@
+import { convertPasswordPolicy } from "./config";
+
+test("convert password policy to regular expression", () => {
+  const passwordPolicy = {
+    whiteSpace: "(?=.*\\s)",
+    highSecurity: "^(?=.*[a-z])(?=.*[A-Z])((?=(.*\\d){2}))",
+    wrong: "@[",
+  };
+  const actual = convertPasswordPolicy(passwordPolicy);
+  expect(actual).toStrictEqual({
+    whiteSpace: /(?=.*\s)/,
+    highSecurity: /^(?=.*[a-z])(?=.*[A-Z])((?=(.*\d){2}))/,
+  });
+});
+
+test("return undefined if no password policy", () => {
+  const actual = convertPasswordPolicy(undefined);
+  expect(actual).toBeUndefined();
+});
diff --git a/src/config.ts b/src/config.ts
index f83172e4b..2d62d646f 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -31,6 +31,24 @@ export const defaultConfig: Config = {
   published: window.origin + "/p/{}/",
 };
 
+export function convertPasswordPolicy(passwordPolicy?: {
+  [key: string]: string;
+}): { [key: string]: RegExp | undefined } | undefined {
+  if (!passwordPolicy) return;
+  return Object.fromEntries(
+    Object.entries(passwordPolicy)
+      .map(([k, v]) => {
+        if (typeof v !== "string") return [k, undefined];
+        try {
+          return [k, new RegExp(v)];
+        } catch {
+          return [k, undefined];
+        }
+      })
+      .filter(i => !!i[1]),
+  );
+}
+
 export default async function loadConfig() {
   if (window.REEARTH_CONFIG) return;
   window.REEARTH_CONFIG = defaultConfig;
@@ -41,14 +59,7 @@ export default async function loadConfig() {
 
   if (!window.REEARTH_CONFIG?.passwordPolicy) return;
 
-  window.REEARTH_CONFIG.passwordPolicy = Object.entries(
-    Object.values(window.REEARTH_CONFIG.passwordPolicy).map((k, v) => {
-      if (typeof v !== "string") return undefined;
-      try {
-        return [k, new RegExp(v)];
-      } catch {
-        return undefined;
-      }
-    }),
-  ) as Config["passwordPolicy"];
+  window.REEARTH_CONFIG.passwordPolicy = convertPasswordPolicy(
+    window.REEARTH_CONFIG.passwordPolicy as { [key: string]: string },
+  );
 }