diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e2decf5..6b3872c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -49,7 +49,7 @@ jobs:
         node-version: "16.x"
     - name: Install tools
       shell: bash
-      run: "gem install --no-document bundler toys && bundle install"
+      run: "gem install --no-document toys && bundle install"
     - name: Test ${{ matrix.task }}
       shell: bash
       run: toys do ${{ matrix.task }} < /dev/null
diff --git a/lib/google/cloud/env/compute_metadata.rb b/lib/google/cloud/env/compute_metadata.rb
index 39a8282..aba7c59 100644
--- a/lib/google/cloud/env/compute_metadata.rb
+++ b/lib/google/cloud/env/compute_metadata.rb
@@ -389,12 +389,12 @@ def lookup_response path,
                             retry_count: :default,
                             retry_timeout: :default
           query = canonicalize_query query
-          raise MetadataServerNotResponding unless gce_check
           if @overrides
             @mutex.synchronize do
               return lookup_override path, query if @overrides
             end
           end
+          raise MetadataServerNotResponding unless gce_check
           retry_count = self.retry_count if retry_count == :default
           retry_count += 1 if retry_count
           retry_timeout = self.retry_timeout if retry_timeout == :default
@@ -845,6 +845,7 @@ def lookup_override path, query
             @existence = :no
             raise MetadataServerNotResponding
           end
+          @existence = :confirmed
           result = @overrides.lookup path, query: query
           result ||= Response.new 404, "Not found", FLAVOR_HEADER
           result
diff --git a/test/helper.rb b/test/helper.rb
index 01e3a7d..6333494 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -16,4 +16,5 @@
 require "minitest/autorun"
 require "minitest/focus"
 require "minitest/rg"
+require "base64"
 require "json"