diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index b3d45b2a4..2e3187f97 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -127,7 +127,7 @@ backend lint:
     - *stack-cache
   script:
     - "ls -a ." # TODO: debug only
-    - "nix shell .#gnumake .#stack --command make backend-lint-prod"
+    - "nix shell .#gnumake .#stack .#tzdata --command \"prepare-env && make backend-lint-prod\""
   before_script: *nix-before
   needs:
     - job: backend dependencies
@@ -164,7 +164,7 @@ backend build:
   cache:
     - *stack-cache
   script:
-    - "nix shell .#gnumake .#coreutils .#stack --command make backend-build-prod"
+    - "nix shell .#gnumake .#coreutils .#stack .#tzdata --command \"prepare-env && make backend-build-prod\""
     - cp $(stack path --dist-dir)/build/hlint/hlint bin/test-hlint
     - cp $(stack path --dist-dir)/build/yesod/yesod bin/test-yesod
   before_script: *nix-before
@@ -249,7 +249,7 @@ uniworx:exe:uniworxload:
 frontend test:
   stage: test
   script:
-    - "nix shell .#gnumake .#nodejs-14_x --command make frontend-test"
+    - "nix shell .#gnumake .#nodejs-14_x .#chromium .#tzdata --command \"prepare-env && make frontend-test\""
   before_script: *nix-before
   cache: *frontend-cache
   needs:
diff --git a/shell.nix b/shell.nix
index 47daa2f68..752198903 100644
--- a/shell.nix
+++ b/shell.nix
@@ -262,21 +262,26 @@ let
 
     git diff $(cut -d '-' -f 1 <(curl -sH 'Accept: text/plain' https://uni2work.ifi.lmu.de/version))
   '';
+
+  prepareEnv = pkgs.writeScriptBin "prepare-env" ''
+    #!${pkgs.zsh}/bin/zsh
+
+    export TZDIR=${pkgs.tzdata}/share/zoneinfo
+    export CHROME_BIN=${pkgs.chromium}/bin/chromium
+
+    echo "prepareEnv has been executed"
+    echo "TZDIR: $TZDIR"
+    echo "CHROME_BIN: $CHROME_BIN"
+  '';
 in pkgs.mkShell {
   name = "fradrive";
   shellHook = ''
     ${pkgs.lib.optionalString (nixpkgsPath != null) ''
       export NIX_PATH=nixpkgs=${nixpkgsPath}
     ''}
-
-    export TZDIR=${pkgs.tzdata}/share/zoneinfo
-    export CHROME_BIN=${pkgs.chromium}/bin/chromium
-
-    echo "shellHook has been executed"
-    echo "TZDIR: $TZDIR"
-    echo "CHROME_BIN: $CHROME_BIN"
+    prepare-env
   '';
-  nativeBuildInputs = [develop inDevelop killallUni2work diffRunning]
+  nativeBuildInputs = [develop inDevelop killallUni2work diffRunning prepareEnv]
   ++ (with pkgs;
     [ stdenv coreutils stack nodejs-14_x postgresql_12 openldap exiftool memcached minio minio-client
       gup reuse pre-commit