diff --git a/lib/appraisal/command.rb b/lib/appraisal/command.rb
index c7c63d75..6de50162 100644
--- a/lib/appraisal/command.rb
+++ b/lib/appraisal/command.rb
@@ -12,13 +12,15 @@ def initialize(command, options = {})
     end
 
     def run
+      run_env = test_environment.merge(env)
+
       Bundler.with_original_env do
         ensure_bundler_is_available
         announce
 
         ENV["BUNDLE_GEMFILE"] = gemfile
         ENV["APPRAISAL_INITIALIZED"] = "1"
-        env.each_pair do |key, value|
+        run_env.each_pair do |key, value|
           ENV[key] = value
         end
 
@@ -79,5 +81,14 @@ def command_as_string
         command
       end
     end
+
+    def test_environment
+      return {} unless ENV["APPRAISAL_UNDER_TEST"] == "1"
+
+      {
+        "GEM_HOME" => ENV["GEM_HOME"],
+        "GEM_PATH" => "",
+      }
+    end
   end
 end
diff --git a/spec/acceptance/bundle_without_spec.rb b/spec/acceptance/bundle_without_spec.rb
index c57c84f4..710c2a63 100644
--- a/spec/acceptance/bundle_without_spec.rb
+++ b/spec/acceptance/bundle_without_spec.rb
@@ -39,7 +39,9 @@
     output = run "appraisal install --without drinks"
 
     expect(output).to include("Bundle complete")
-    expect(output).to include("Gems in the group drinks were not installed.")
+    expect(output).to(
+      match(/Gems in the group ['"]?drinks['"]? were not installed/)
+    )
     expect(output).not_to include("orange_juice")
     expect(output).not_to include("coffee")
     expect(output).not_to include("soda")
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 68deffc9..d3328e05 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -5,6 +5,7 @@
 
 PROJECT_ROOT = File.expand_path(File.join(File.dirname(__FILE__), '..')).freeze
 TMP_GEM_ROOT = File.join(PROJECT_ROOT, "tmp", "gems")
+ENV["APPRAISAL_UNDER_TEST"] = "1"
 
 RSpec.configure do |config|
   config.raise_errors_for_deprecations!