diff --git a/Dockerfile-alpine b/Dockerfile-alpine
index 73c45225..1c162d23 100644
--- a/Dockerfile-alpine
+++ b/Dockerfile-alpine
@@ -1,5 +1,7 @@
 FROM ruby:2.5.1-alpine
 
+ENV LANG=C.UTF-8
+
 WORKDIR /devdocs
 
 COPY . /devdocs