diff --git a/spec/lib/polariscope/scanner/gem_versions_spec.rb b/spec/lib/polariscope/scanner/gem_versions_spec.rb
index a3a5ccc..17841eb 100644
--- a/spec/lib/polariscope/scanner/gem_versions_spec.rb
+++ b/spec/lib/polariscope/scanner/gem_versions_spec.rb
@@ -27,14 +27,20 @@
   end
 
   describe '#versions_for' do
-    let(:dependencies) { ['devise', 'rails'] }
-
     before { allow(Polariscope::Scanner::RubyVersions).to receive(:available_versions) }
 
-    it 'returns only distinct versions for given gem name' do
-      expect(scanner.versions_for('devise').map(&:to_s)).to contain_exactly('4.6.2', '4.5.0')
+    context 'when ruby is not in dependencies' do
+      let(:dependencies) { ['devise', 'rails'] }
+
+      it 'returns distinct versions for given gem name' do
+        expect(scanner.versions_for('devise').map(&:to_s)).to contain_exactly('4.6.2', '4.5.0')
+      end
+
+      it "doesn't fetch ruby versions" do
+        scanner
 
-      expect(Polariscope::Scanner::RubyVersions).not_to have_received(:available_versions)
+        expect(Polariscope::Scanner::RubyVersions).not_to have_received(:available_versions)
+      end
     end
 
     context 'when ruby is in dependencies' do