diff --git a/spec/models/kalibro_range_spec.rb b/spec/models/kalibro_range_spec.rb
index 06179f4..8ba1317 100644
--- a/spec/models/kalibro_range_spec.rb
+++ b/spec/models/kalibro_range_spec.rb
@@ -69,6 +69,16 @@
           expect(subject.as_json['end']).to eq('INF')
         end
       end
+
+      context 'with negative infinity end' do
+        before do
+          subject.end = -Float::INFINITY
+        end
+
+        it 'is expected to convert to INF' do
+          expect(subject.as_json['end']).to eq('-INF')
+        end
+      end
     end
   end
 
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index fb16b33..776b8b3 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -5,7 +5,7 @@
   # Minimum coverage is only desired on CI tools when building the environment. CI is a
   # default environment variable used by Travis. For reference, see here:
   # https://docs.travis-ci.com/user/environment-variables/#Default-Environment-Variables
-  minimum_coverage 100 if ENV["CI"] == 'true'
+  minimum_coverage 100 if ENV['CI'] == 'true'
   coverage_dir 'coverage/rspec'
 
   add_filter '/spec/'