diff --git a/lib/ldclient-rb/impl/diagnostic_events.rb b/lib/ldclient-rb/impl/diagnostic_events.rb
index 4c61a905..13a55756 100644
--- a/lib/ldclient-rb/impl/diagnostic_events.rb
+++ b/lib/ldclient-rb/impl/diagnostic_events.rb
@@ -79,7 +79,7 @@ def self.make_config_data(config)
           streamingDisabled: !config.stream?,
           userKeysCapacity: config.user_keys_capacity,
           userKeysFlushIntervalMillis: self.seconds_to_millis(config.user_keys_flush_interval),
-          usingProxy: ENV.has_key?('http_proxy') || ENV.has_key?('https_proxy') || ENV.has_key?('HTTP_PROXY'),
+          usingProxy: ENV.has_key?('http_proxy') || ENV.has_key?('https_proxy') || ENV.has_key?('HTTP_PROXY') || ENV.has_key?('HTTPS_PROXY'),
           usingRelayDaemon: config.use_ldd?,
         }
         ret
diff --git a/spec/diagnostic_events_spec.rb b/spec/diagnostic_events_spec.rb
index 0c4ef058..7e1bce7f 100644
--- a/spec/diagnostic_events_spec.rb
+++ b/spec/diagnostic_events_spec.rb
@@ -79,13 +79,15 @@ def expected_default_config
           end
         end
 
-        it "detects proxy" do
-          begin
-            ENV["http_proxy"] = 'http://my-proxy'
-            event = default_acc.create_init_event(Config.new)
-            expect(event[:configuration][:usingProxy]).to be true
-          ensure
-            ENV["http_proxy"] = nil
+        ['http_proxy', 'https_proxy', 'HTTP_PROXY', 'HTTPS_PROXY'].each do |name|
+          it "detects proxy #{name}" do
+            begin
+              ENV[name] = 'http://my-proxy'
+              event = default_acc.create_init_event(Config.new)
+              expect(event[:configuration][:usingProxy]).to be true
+            ensure
+              ENV[name] = nil
+            end
           end
         end