diff --git a/Dockerfile b/Dockerfile
index 04c3363..6502928 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -13,7 +13,7 @@ RUN locale-gen en_US.UTF-8
 
 ENV LANGUAGE=en_US.UTF-8
 ENV LC_ALL=en_US.UTF-8
-ENV LC_CTYPE=UTF-8
+ENV LC_CTYPE=en_US.UTF-8
 ENV LANG=en_US.UTF-8
 ENV TERM xterm
 
diff --git a/Dockerfile-71 b/Dockerfile-71
index 8c60bdc..b0ab29d 100644
--- a/Dockerfile-71
+++ b/Dockerfile-71
@@ -13,7 +13,7 @@ RUN locale-gen en_US.UTF-8
 
 ENV LANGUAGE=en_US.UTF-8
 ENV LC_ALL=en_US.UTF-8
-ENV LC_CTYPE=UTF-8
+ENV LC_CTYPE=en_US.UTF-8
 ENV LANG=en_US.UTF-8
 ENV TERM xterm