diff --git a/shells/dodona-docs.nix b/shells/dodona-docs.nix
new file mode 100644
index 00000000..2099dc92
--- /dev/null
+++ b/shells/dodona-docs.nix
@@ -0,0 +1,12 @@
+let
+  pkgs = import <nixpkgs> { };
+in
+pkgs.mkShell {
+  buildInputs = with pkgs; [
+    nodejs-12_x
+    yarn
+  ];
+  shellHook = ''
+    export PUPPETEER_EXECUTABLE_PATH="${pkgs.ungoogled-chromium}/bin/chromium"
+  '';
+}
diff --git a/shells/dodona.nix b/shells/dodona.nix
index 5c065df4..f7562372 100644
--- a/shells/dodona.nix
+++ b/shells/dodona.nix
@@ -6,7 +6,7 @@ pkgs.mkShell {
     chromedriver
     libmysqlclient
     nodejs-12_x
-    ruby_2_7
+    ruby
     yarn
     zlib
     (
diff --git a/shells/r.nix b/shells/r.nix
index 13259193..51a1c316 100644
--- a/shells/r.nix
+++ b/shells/r.nix
@@ -1,18 +1,18 @@
 let
   pkgs = import <nixpkgs> { };
 in
-  pkgs.mkShell {
-    buildInputs = [
-      (pkgs.rWrapper.override {
-        packages = with pkgs.rPackages; [
-          base64enc
-          dplyr
-          dslabs
-          jsonlite
-          knitr
-          R6
-          rlang
-        ];
-      })
-    ];
-  }
+pkgs.mkShell {
+  buildInputs = [
+    (pkgs.rWrapper.override {
+      packages = with pkgs.rPackages; [
+        base64enc
+        dplyr
+        dslabs
+        jsonlite
+        knitr
+        R6
+        rlang
+      ];
+    })
+  ];
+}