diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 7d19372..f8d64ae 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -29,19 +29,40 @@ codestyle:
 
 
 
-build_docker:
+build_docker_tag:
   stage: build
+  image:
+    name: gcr.io/kaniko-project/executor
+    entrypoint: [""]
   script:
-  - docker build -t "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_SHA" -f package/docker/Dockerfile .
-  - docker tag "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_SHA" "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_REF_NAME"
-  - if [[ -n "$CI_COMMIT_TAG" ]]; then docker tag "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_SHA" "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_TAG"; fi
-  - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD registry.gitlab.com
-  - docker push "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_SHA"
-  - docker push "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_REF_NAME"
-  - if [[ -n "$CI_COMMIT_TAG" ]]; then docker push "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_TAG"; fi
+  - mkdir -p /kaniko/.docker
+  - echo "{\"auths\":{\"${CI_REGISTRY}\":{\"auth\":\"$(printf "%s:%s" "${CI_REGISTRY_USER}" "${CI_REGISTRY_PASSWORD}" | base64 | tr -d '\n')\"}}}" > /kaniko/.docker/config.json
+  - >-
+    /kaniko/executor
+    --context .
+    --dockerfile package/docker/Dockerfile
+    --destination "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_SHA"
+    --destination "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_REF_NAME"
+    --destination "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_TAG"
+  only:
+  - tags
+
+build_docker_staging:
+  stage: build
+  image:
+    name: gcr.io/kaniko-project/executor
+    entrypoint: [""]
+  script:
+  - mkdir -p /kaniko/.docker
+  - echo "{\"auths\":{\"${CI_REGISTRY}\":{\"auth\":\"$(printf "%s:%s" "${CI_REGISTRY_USER}" "${CI_REGISTRY_PASSWORD}" | base64 | tr -d '\n')\"}}}" > /kaniko/.docker/config.json
+  - >-
+    /kaniko/executor
+    --context .
+    --dockerfile package/docker/Dockerfile
+    --destination "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_SHA"
+    --destination "registry.gitlab.com/s3lph/matemat:$CI_COMMIT_REF_NAME"
   only:
   - staging
-  - tags
 
 build_wheel:
   stage: build
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54ae939..892b56b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,11 +3,12 @@
 <!-- BEGIN RELEASE v0.2.10 -->
 ## Version 0.2.10
 
-Feature release
+Feature release, Python 3.9
 
 ### Changes
 
 <!-- BEGIN CHANGES 0.2.10 -->
+- Use Python 3.9 by default
 - Feature: Let users transfer funds to another account
 <!-- END CHANGES 0.2.10 -->
 
diff --git a/package/docker/Dockerfile b/package/docker/Dockerfile
index fb2166d..19c503a 100644
--- a/package/docker/Dockerfile
+++ b/package/docker/Dockerfile
@@ -1,5 +1,5 @@
 
-FROM python:3.7-alpine
+FROM python:3.9-alpine
 
 ADD . /
 RUN mkdir -p /var/matemat/db /var/matemat/upload \