diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cb03a339..dc673572 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,10 +14,14 @@ jobs:
         ruby:
           - 2.7.6
           - 3.0.4
+          - truffleruby-22.3.0
         os:
           - ubuntu-latest
           - macos-latest
           - windows-latest
+        exclude:
+          - os: windows-latest
+            ruby: truffleruby-22.3.0
     defaults:
       run:
         working-directory: examples/gem
diff --git a/examples/gem/.bazelrc b/examples/gem/.bazelrc
index e2c239b4..6d152190 100644
--- a/examples/gem/.bazelrc
+++ b/examples/gem/.bazelrc
@@ -1,3 +1,7 @@
 startup --windows_enable_symlinks
 build --enable_runfiles
 test --test_output=errors
+
+# TruffleRuby needs $HOME for File#expand_path to work.
+build --action_env=HOME
+test --test_env=HOME
diff --git a/examples/gem/Gemfile.lock b/examples/gem/Gemfile.lock
index a367a929..57625f0c 100644
--- a/examples/gem/Gemfile.lock
+++ b/examples/gem/Gemfile.lock
@@ -10,6 +10,7 @@ GEM
     ast (2.4.2)
     diff-lcs (1.5.0)
     json (2.6.2)
+    json (2.6.2-java)
     parallel (1.22.1)
     parser (3.1.2.1)
       ast (~> 2.4.1)
@@ -47,6 +48,7 @@ GEM
 
 PLATFORMS
   ruby
+  universal-java-18
   x64-mingw32
 
 DEPENDENCIES
diff --git a/ruby/private/gem_build.bzl b/ruby/private/gem_build.bzl
index 0efd7bd5..9157c843 100644
--- a/ruby/private/gem_build.bzl
+++ b/ruby/private/gem_build.bzl
@@ -36,6 +36,7 @@ def _rb_gem_build_impl(ctx):
         executable = toolchain.ruby,
         arguments = [args],
         outputs = [ctx.outputs.gem],
+        use_default_shell_env = True,
     )
 
 rb_gem_build = rule(