diff --git a/9.4/Dockerfile b/9.4/Dockerfile
index 27ff03e13a..31ca0c8fb3 100644
--- a/9.4/Dockerfile
+++ b/9.4/Dockerfile
@@ -16,8 +16,8 @@ RUN apt-get update && apt-get install -y curl && rm -rf /var/lib/apt/lists/* \
 
 # make the "en_US.UTF-8" locale so postgres will be utf-8 enabled by default
 RUN apt-get update && apt-get install -y locales && rm -rf /var/lib/apt/lists/* \
-	&& localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8
-ENV LANG en_US.utf8
+	&& localedef -i ja_JP -c -f UTF-8 -A /usr/share/locale/locale.alias ja_JP.UTF-8
+ENV LANG ja_JP.utf8
 
 RUN mkdir /docker-entrypoint-initdb.d