diff --git a/test/docker/ubuntu1604 b/test/docker/ubuntu1604
index b58a5fe46..13904007e 100644
--- a/test/docker/ubuntu1604
+++ b/test/docker/ubuntu1604
@@ -1,10 +1,10 @@
 FROM ubuntu:16.04
 
 RUN apt-get update
-RUN apt-get install -y build-essential cmake git uuid-dev libgnutls28-dev faketime
-RUN apt-get install -y python3
+RUN apt-get install -y build-essential cmake git uuid-dev libgnutls28-dev faketime locales python3
 
 # Setup language environment
+RUN locale-gen en_US.UTF-8
 ENV LC_ALL en_US.UTF-8
 ENV LANG en_US.UTF-8
 ENV LANGUAGE en_US.UTF-8
diff --git a/test/docker/ubuntu1804 b/test/docker/ubuntu1804
index a7d97551b..36bdb4500 100644
--- a/test/docker/ubuntu1804
+++ b/test/docker/ubuntu1804
@@ -1,10 +1,10 @@
 FROM ubuntu:18.04
 
 RUN apt-get update
-RUN apt-get install -y build-essential cmake git uuid-dev libgnutls28-dev faketime
-RUN apt-get install -y python3
+RUN apt-get install -y build-essential cmake git uuid-dev libgnutls28-dev faketime locales python3
 
 # Setup language environment
+RUN locale-gen en_US.UTF-8
 ENV LC_ALL en_US.UTF-8
 ENV LANG en_US.UTF-8
 ENV LANGUAGE en_US.UTF-8