diff --git a/kanken_online/auth.py b/kanken_online/auth.py
index 6d8cc73..50069b0 100644
--- a/kanken_online/auth.py
+++ b/kanken_online/auth.py
@@ -14,9 +14,9 @@ def register():
         error = None
 
         if not username:
-            error = "Username is required."
+            error = "username_required"
         elif not password:
-            error = "Password is required."
+            error = "password_required"
 
         if error is None:
             try:
@@ -46,9 +46,9 @@ def login():
         ).fetchone()
 
         if user is None:
-            error = "Incorrect username."
+            error = "incorrect_username"
         elif not check_password_hash(user["password"], password):
-            error = "Incorrect password."
+            error = "incorrect_password"
 
         if error is None:
             session.clear()
diff --git a/kanken_online/lang.py b/kanken_online/lang.py
index b99beb2..6d18558 100644
--- a/kanken_online/lang.py
+++ b/kanken_online/lang.py
@@ -12,7 +12,9 @@ EXISTING_STRINGS = {
     "search",
     "search_placeholder",
     "include_kanji",
-    "include_kotoba"
+    "include_kotoba",
+    "username_required",
+    "password_required"
 }
 
 ENGLISH = {
@@ -29,7 +31,11 @@ ENGLISH = {
     "search": "Search",
     "search_placeholder": "Enter kanji or word",
     "include_kanji": "Include kanji",
-    "include_kotoba": "Include kotoba"
+    "include_kotoba": "Include kotoba",
+    "username_required": "Username required.",
+    "password_required": "Password required.",
+    "incorrect_username": "Incorrect username.",
+    "incorrect_password": "Incorrect password."
 }
 
 JAPANESE = {
@@ -47,6 +53,10 @@ JAPANESE = {
     "search_placeholder": "漢字・言葉を入力",
     "include_kanji": "漢字を含む",
     "include_kotoba": "言葉を含む",
+    "username_required": "ユーザー名が必要です",
+    "password_required": "パスワードが必要です",
+    "incorrect_username": "ユーザー名が違います",
+    "incorrect_password": "パスワードが違います"
 }
 
 LANGUAGES = [