diff --git a/tools/docker/Dockerfile.test_python b/tools/docker/Dockerfile.test_python
index 57b4e628bf..6dca18d346 100644
--- a/tools/docker/Dockerfile.test_python
+++ b/tools/docker/Dockerfile.test_python
@@ -7,10 +7,6 @@ WORKDIR /workspace
 COPY ./scripts/install_basics.sh .
 RUN ./install_basics.sh
 
-# set a proper unicode-enabled locale, see https://hub.docker.com/_/ubuntu?tab=description
-RUN localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8
-ENV LANG en_US.UTF-8
-
 COPY ./scripts/install_python.sh .
 RUN ./install_python.sh
 
diff --git a/tools/docker/scripts/install_basics.sh b/tools/docker/scripts/install_basics.sh
index 152fa0b31c..d149a5aa1f 100755
--- a/tools/docker/scripts/install_basics.sh
+++ b/tools/docker/scripts/install_basics.sh
@@ -7,7 +7,6 @@ if grep -q "Ubuntu" /etc/os-release ; then
     apt-get update -qq
     apt-get install -qq --no-install-recommends \
         ca-certificates                         \
-        locales                                 \
         git                                     \
         less                                    \
         nano                                    \
@@ -15,7 +14,6 @@ if grep -q "Ubuntu" /etc/os-release ; then
         rsync                                   \
         wget
     rm -rf /var/lib/apt/lists/*
-    locale-gen "en_US.UTF-8"
     echo "done."
 
 elif grep -q "Fedora" /etc/os-release ; then
diff --git a/tools/regtesting/do_regtest b/tools/regtesting/do_regtest
index fd6f4c10fd..f7e8d9d69f 100755
--- a/tools/regtesting/do_regtest
+++ b/tools/regtesting/do_regtest
@@ -10,7 +10,9 @@
 # command line argument passing
 #
 ###################################################################################
-export LC_ALL=en_US.UTF-8
+
+# ensure error messages are in English
+export LC_ALL=C
 
 # init
 dir_base=$PWD
diff --git a/tools/toolchain/Dockerfile b/tools/toolchain/Dockerfile
index cb089c1911..af05e1a40b 100644
--- a/tools/toolchain/Dockerfile
+++ b/tools/toolchain/Dockerfile
@@ -15,8 +15,6 @@ USER root
 COPY ./install_requirements*.sh ./
 RUN ./install_requirements.sh ${BASE_IMAGE}
 
-ENV LANG en_US.UTF-8
-
 # copy helper scripts
 WORKDIR /opt/cp2k-toolchain
 RUN mkdir scripts
diff --git a/tools/toolchain/Dockerfile.cuda_mkl b/tools/toolchain/Dockerfile.cuda_mkl
index 89ac230afd..c176dae858 100644
--- a/tools/toolchain/Dockerfile.cuda_mkl
+++ b/tools/toolchain/Dockerfile.cuda_mkl
@@ -11,8 +11,6 @@ ARG LIBINT_LMAX=5
 COPY ./install_requirements_ubuntu.sh .
 RUN ./install_requirements_ubuntu.sh
 
-ENV LANG en_US.UTF-8
-
 # Install some more Ubuntu packages.
 RUN apt-get update -qq && apt-get install -qq --no-install-recommends \
     gfortran                                                          \
diff --git a/tools/toolchain/Dockerfile.ubuntu_nompi b/tools/toolchain/Dockerfile.ubuntu_nompi
index 0447626cf4..5fce33a650 100644
--- a/tools/toolchain/Dockerfile.ubuntu_nompi
+++ b/tools/toolchain/Dockerfile.ubuntu_nompi
@@ -21,7 +21,6 @@ RUN export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true && \
     git \
     less \
     libtool \
-    locales \
     make \
     nano \
     pkg-config \
@@ -40,10 +39,6 @@ RUN export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true && \
     libhdf5-dev \
    && rm -rf /var/lib/apt/lists/*
 
-# generate a unicode-enabled locale, see https://hub.docker.com/_/ubuntu?tab=description
-RUN localedef -i C -c -f UTF-8 -A /usr/share/locale/locale.alias C.UTF-8
-ENV LANG en_US.UTF-8
-
 # Create links.
 RUN ln -sf gcc-${GCC_VERSION}      /usr/bin/gcc  && \
     ln -sf g++-${GCC_VERSION}      /usr/bin/g++  && \
diff --git a/tools/toolchain/install_requirements_fedora.sh b/tools/toolchain/install_requirements_fedora.sh
index 5668259ba7..2143569d92 100755
--- a/tools/toolchain/install_requirements_fedora.sh
+++ b/tools/toolchain/install_requirements_fedora.sh
@@ -15,7 +15,6 @@ dnf -qy install                             \
     diffutils                               \
     g++                                     \
     git                                     \
-    glibc-langpack-en                       \
     less                                    \
     libtool                                 \
     make                                    \
diff --git a/tools/toolchain/install_requirements_ubuntu.sh b/tools/toolchain/install_requirements_ubuntu.sh
index 208ab74663..de43f07845 100755
--- a/tools/toolchain/install_requirements_ubuntu.sh
+++ b/tools/toolchain/install_requirements_ubuntu.sh
@@ -21,7 +21,6 @@ apt-get install -qq --no-install-recommends \
     git                                     \
     less                                    \
     libtool                                 \
-    locales                                 \
     make                                    \
     nano                                    \
     patch                                   \
@@ -36,5 +35,4 @@ apt-get install -qq --no-install-recommends \
 
 rm -rf /var/lib/apt/lists/*
 
-# generate a unicode-enabled locale, see https://hub.docker.com/_/ubuntu?tab=description
-localedef -i C -c -f UTF-8 -A /usr/share/locale/locale.alias C.UTF-8
+#EOF