diff --git a/dot_zshenv b/dot_zshenv
index 58102bf..4159009 100644
--- a/dot_zshenv
+++ b/dot_zshenv
@@ -9,7 +9,7 @@ GPG_TTY=$(tty)
 export GPG_TTY
 
 # LANGUAGE
-if locale -a | grep -q ^ja_JP; then
+if locale -a | grep -qi ^ja_JP; then
   export LANG=ja_JP.UTF-8
 else
   export LANG=en_US.UTF-8