diff --git a/Dockerfile.ruby-2.1 b/Dockerfile.ruby-2.1
index 75c55d6..35cd5f1 100644
--- a/Dockerfile.ruby-2.1
+++ b/Dockerfile.ruby-2.1
@@ -1,8 +1,14 @@
 FROM ruby:2.1
 
-ENV PACKAGES="git-core" \
-	LC_ALL=en_US.UTF-8
+ENV PACKAGES="git-core"
 
 ADD / /
 RUN /scripts/install-essentials
+
+# Set UTF-8 http://jaredmarkell.com/docker-and-locales/
+# Must be set after install-essentials is run
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
 RUN /scripts/install-phantomjs
diff --git a/Dockerfile.ruby-2.2 b/Dockerfile.ruby-2.2
index 3d1e2f1..d0e1760 100644
--- a/Dockerfile.ruby-2.2
+++ b/Dockerfile.ruby-2.2
@@ -1,8 +1,14 @@
 FROM ruby:2.2
 
-ENV PACKAGES="git-core" \
-	LC_ALL=en_US.UTF-8
+ENV PACKAGES="git-core"
 
 ADD / /
 RUN /scripts/install-essentials
+
+# Set UTF-8 http://jaredmarkell.com/docker-and-locales/
+# Must be set after install-essentials is run
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
 RUN /scripts/install-phantomjs
diff --git a/Dockerfile.ruby-2.3 b/Dockerfile.ruby-2.3
index 79afc2f..d8b29e6 100644
--- a/Dockerfile.ruby-2.3
+++ b/Dockerfile.ruby-2.3
@@ -1,8 +1,14 @@
 FROM ruby:2.3
 
-ENV PACKAGES="git-core" \
-	LC_ALL=en_US.UTF-8
+ENV PACKAGES="git-core"
 
 ADD / /
 RUN /scripts/install-essentials
+
+# Set UTF-8 http://jaredmarkell.com/docker-and-locales/
+# Must be set after install-essentials is run
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
 RUN /scripts/install-phantomjs
diff --git a/Dockerfile.www-gitlab-com b/Dockerfile.www-gitlab-com
index 9be89f6..264144a 100644
--- a/Dockerfile.www-gitlab-com
+++ b/Dockerfile.www-gitlab-com
@@ -1,7 +1,14 @@
 FROM ruby:2.1
 
-ENV PACKAGES="git-core nodejs pandoc texlive-latex-recommended texlive-xetex texlive-fonts-recommended ed" \
-	LC_ALL=en_US.UTF-8
+ENV PACKAGES="git-core nodejs pandoc texlive-latex-recommended texlive-xetex texlive-fonts-recommended ed"
 
 ADD / /
 RUN /scripts/install-essentials
+
+# Set UTF-8 http://jaredmarkell.com/docker-and-locales/
+# Must be set after install-essentials is run
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
+RUN rm -rf /var/lib/apt/lists/*
diff --git a/scripts/install-essentials b/scripts/install-essentials
index e4bb75e..f6a8692 100755
--- a/scripts/install-essentials
+++ b/scripts/install-essentials
@@ -4,7 +4,7 @@ set -xeo pipefail
 
 apt-get update
 apt-get install -y \
-	curl wget build-essential \
+	curl wget build-essential apt-utils locales \
 	libssl-dev libyaml-dev libreadline6-dev zlib1g-dev \
 	libncurses5-dev libffi-dev libgdbm3 libgdbm-dev \
 	ca-certificates libyaml-dev checkinstall libxml2-dev \
@@ -13,4 +13,13 @@ apt-get install -y \
 	libkrb5-dev postgresql-client mysql-client unzip \
 	$PACKAGES
 
+# Set UTF-8
+# http://stackoverflow.com/a/3182519/2137281
+LOC=$'LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8'
+echo "$LOC" > /etc/environment
+cat /etc/environment
+locale-gen "en_US en_US.UTF-8"
+dpkg-reconfigure locales -f noninteractive -p critical
+locale -a
+
 rm -rf /var/lib/apt/lists/*