diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 87c4a8a7788075a4143c2ef86d44cad01e79aa35..c3dba454bb08f1d4a1c612523e050b00e7175a51 100755
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -37,7 +37,7 @@ linter_dockerfile:
     when: always
 
 build_docker:
-  image: docker:stable
+  image: ${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}/docker:stable
   services:
     - docker:dind
   before_script:
@@ -49,7 +49,7 @@ build_docker:
         --tag $CONTAINER_IMAGE:$CI_COMMIT_SHA 
         --file docker/Dockerfile
         --build-arg BUILDKIT_INLINE_CACHE=1
-        --build-arg REF_BASE_IMAGE=$REF_BASE_IMAGE
+        --build-arg REGISTRY_DOMAIN=${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}
         "."
   after_script:
     - echo $CI_JOB_TOKEN | docker login -u $CI_REGISTRY_USER --password-stdin $CI_REGISTRY
@@ -59,7 +59,7 @@ build_docker:
 
 
 test_pytest:
-  image: docker:stable
+  image: ${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}/docker:stable
   services:
     - docker:dind
   variables:
@@ -82,7 +82,7 @@ test_pytest:
   
 
 export_jupyternb:
-  image: docker:stable
+  image: ${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}/docker:stable
   services:
     - docker:dind
   variables:
@@ -102,7 +102,7 @@ export_jupyternb:
   needs: ["build_docker"]
 
 pages:
-  image: python:3.7-alpine
+  image: ${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}/python:3.7-alpine
   script:
   - pip install -U sphinx
   - pip install sphinx-rtd-theme
diff --git a/docker/Dockerfile b/docker/Dockerfile
index ec8d9246bbc91edeba26aa2f3fdada3abce6c9d0..40c7a65e04c31583feaeb94382eefe37e602d8c4 100755
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,6 +1,6 @@
-ARG REF_BASE_IMAGE=sagemath/sagemath:9.0-py3
+ARG REGISTRY_DOMAIN="docker.io/library"
 # hadolint ignore=DL3006
-FROM $REF_BASE_IMAGE
+FROM ${REGISTRY_DOMAIN}/sagemath/sagemath:9.0-py3
 
 ENV PYTHONUNBUFFERED 1