diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 08122d8dd589b25b955d92ddc1b7299a5040cb35..60d66f4d88a3583ed7be895063d627302207447d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,7 +6,7 @@ variables:
   DOCKER_LOGIN:
     docker login -u $DOCKER_HUB_USER -p $DOCKER_HUB_PW
   DUNE_ENV_IMAGE:
-    dorie/dune-env:2.6
+    dorie/dune-env:2.5.1
   CMAKE_FLAGS:
     -DDUNE_PYTHON_VIRTUALENV_SETUP=True
     -DDUNE_PYTHON_ALLOW_GET_PIP=True
@@ -39,9 +39,7 @@ setup:dune-env:
   before_script:
     - $DOCKER_LOGIN
   script:
-    - docker build -f docker/dune-env.dockerfile
-      --build-arg DUNE_ENV_IMAGE=$DUNE_ENV_IMAGE PROCNUM=$CPUS_DIND
-      -t $DUNE_ENV_IMAGE .
+    - docker build -f docker/dune-env.dockerfile --build-arg PROCNUM=$CPUS_DIND -t $DUNE_ENV_IMAGE .
     - docker push $DUNE_ENV_IMAGE
 
 prep:update-dune:
@@ -59,9 +57,7 @@ prep:update-dune:
   before_script:
     - $DOCKER_LOGIN
   script:
-    - docker build -f docker/dune-env-update.dockerfile
-      --build-arg DUNE_ENV_IMAGE=$DUNE_ENV_IMAGE PROCNUM=$CPUS_DIND
-      -t $DUNE_ENV_IMAGE .
+    - docker build -f docker/dune-env-update.dockerfile --build-arg PROCNUM=$CPUS_DIND -t $DUNE_ENV_IMAGE .
     - docker push $DUNE_ENV_IMAGE
 
 build:main:
@@ -176,9 +172,7 @@ deploy:dockerhub-devel:
   before_script:
     - $DOCKER_LOGIN
   script:
-    - docker build -f docker/dorie.dockerfile
-      --build-arg DUNE_ENV_IMAGE=$DUNE_ENV_IMAGE PROCNUM=$CPUS_DIND
-      -t dorie/dorie:devel .
+    - docker build -f docker/dorie.dockerfile --build-arg PROCNUM=$CPUS_DIND -t dorie/dorie:devel .
     - docker push dorie/dorie:devel
 
 deploy:dockerhub-stable:
@@ -195,7 +189,5 @@ deploy:dockerhub-stable:
   before_script:
     - $DOCKER_LOGIN
   script:
-    - docker build -f docker/dorie.dockerfile
-      --build-arg DUNE_ENV_IMAGE=$DUNE_ENV_IMAGE PROCNUM=$CPUS_DIND
-      -t dorie/dorie:$CI_COMMIT_TAG .
+    - docker build -f docker/dorie.dockerfile --build-arg PROCNUM=$CPUS_DIND -t dorie/dorie:$CI_COMMIT_TAG .
     - docker push dorie/dorie:$CI_COMMIT_TAG
diff --git a/docker/dorie.dockerfile b/docker/dorie.dockerfile
index d043780a3de4e468cb471c05ac7855452a5fa080..92857c95545d058c0e6993995f817720d11605af 100644
--- a/docker/dorie.dockerfile
+++ b/docker/dorie.dockerfile
@@ -1,5 +1,4 @@
-ARG DUNE_ENV_IMAGE=dorie/dune-env
-FROM $DUNE_ENV_IMAGE
+FROM dorie/dune-env:2.5.1
 LABEL maintainer="lriedel@iup.uni-heidelberg.de"
 # number of cores for parallel builds
 ARG PROCNUM=1
diff --git a/docker/dune-env-update.dockerfile b/docker/dune-env-update.dockerfile
index f4d988d32011f5dfb5f655afb7e6eb73d565d2a6..8670923c793a42a6a26c499bdb5641cd2213d31e 100644
--- a/docker/dune-env-update.dockerfile
+++ b/docker/dune-env-update.dockerfile
@@ -1,5 +1,4 @@
-ARG DUNE_ENV_IMAGE=dorie/dune-env
-FROM $DUNE_ENV_IMAGE
+FROM dorie/dune-env:2.5.1
 LABEL maintainer="lriedel@iup.uni-heidelberg.de"
 # number of cores for parallel builds
 ARG PROCNUM=1
diff --git a/docker/dune-env.dockerfile b/docker/dune-env.dockerfile
index b0444d9c599fde7dc432633a916f2133a0ef03d3..f13c42293e37d5cce875324450729e3b6bde89fc 100644
--- a/docker/dune-env.dockerfile
+++ b/docker/dune-env.dockerfile
@@ -31,16 +31,16 @@ RUN rm -rf /var/lib/apt/lists/* \
 ENV LANG en_US.utf8
 
 WORKDIR /opt/dune
-RUN git clone https://gitlab.dune-project.org/staging/dune-uggrid.git -b releases/2.6 \
+RUN git clone https://gitlab.dune-project.org/staging/dune-uggrid.git -b releases/2.5 \
     && git clone https://gitlab.dune-project.org/oklein/dune-randomfield.git -b master \
-    && git clone https://gitlab.dune-project.org/core/dune-common.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/core/dune-geometry.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/core/dune-grid.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/core/dune-istl.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/core/dune-localfunctions.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/staging/dune-functions.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/pdelab/dune-pdelab.git -b releases/2.6 \
-    && git clone https://gitlab.dune-project.org/staging/dune-typetree.git -b releases/2.6 \
+    && git clone https://gitlab.dune-project.org/core/dune-common.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/core/dune-geometry.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/core/dune-grid.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/core/dune-istl.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/core/dune-localfunctions.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/staging/dune-functions.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/pdelab/dune-pdelab.git -b releases/2.5 \
+    && git clone https://gitlab.dune-project.org/staging/dune-typetree.git -b releases/2.5 \
     && git clone https://gitlab.dune-project.org/quality/dune-testtools.git -b master
 
 WORKDIR /opt/dune