diff --git a/README.md b/README.md
index 772e3c3c..88969487 100644
--- a/README.md
+++ b/README.md
@@ -8,4 +8,6 @@
 
 * Edit the `shell.nix` file so that it contains `import /path/to/this/repo/shells/your-new-file.nix`.
 
+* For shells that have a shellHook that exports environment containing computed directories (e.g. the git root or the current working directory), add `eval "$shellHook"` to your `.envrc`.
+
 * Execute `direnv allow` to load the `.envrc` file which in turn uses `lorri` to load your `shell.nix` file.
diff --git a/programs/git/default.nix b/programs/git/default.nix
index 08b81589..6d3d20cc 100644
--- a/programs/git/default.nix
+++ b/programs/git/default.nix
@@ -23,7 +23,7 @@
         ".envrc"
         "shell.nix"
         # Ruby dependencies in source tree
-        "/vendor/bundler"
+        "/vendor/rubygems"
         "**/*.patch"
       ];
       userEmail = config.custom.git.email;
diff --git a/shells/accentor-api.nix b/shells/accentor-api.nix
index 606baeb2..45a73348 100644
--- a/shells/accentor-api.nix
+++ b/shells/accentor-api.nix
@@ -49,5 +49,7 @@ pkgs.mkShell {
       listen_addresses = '''
       unix_socket_directories = '$PGHOST'
     HERE
+    export GEM_HOME="$PWD/vendor/rubygems"
+    export PATH="$GEM_HOME/bin:$PATH"
   '';
 }
diff --git a/shells/dodona.nix b/shells/dodona.nix
index 35357a0e..dad579b7 100644
--- a/shells/dodona.nix
+++ b/shells/dodona.nix
@@ -50,5 +50,7 @@ pkgs.mkShell {
   ];
   shellHook = ''
     export DATABASE_URL="mysql2://root:dodona@127.0.0.1:3306/dodona"
+    export GEM_HOME="$PWD/vendor/rubygems"
+    export PATH="$GEM_HOME/bin:$PATH"
   '';
 }