diff --git a/lib/prometheus_exporter/ext/metric/gauge_with_time.rb b/lib/prometheus_exporter/ext/metric/gauge_with_time.rb
index 930a2d1..47a9ea2 100644
--- a/lib/prometheus_exporter/ext/metric/gauge_with_time.rb
+++ b/lib/prometheus_exporter/ext/metric/gauge_with_time.rb
@@ -3,7 +3,7 @@
 require 'prometheus_exporter/metric'
 
 module PrometheusExporter::Ext::Metric
-  class GaugeWithTime < Gauge
+  class GaugeWithTime < PrometheusExporter::Metric::Gauge
     attr_reader :timestamps
 
     def reset!
diff --git a/lib/prometheus_exporter/ext/metric/type_registry.rb b/lib/prometheus_exporter/ext/metric/type_registry.rb
index fe56eb2..aaa03d5 100644
--- a/lib/prometheus_exporter/ext/metric/type_registry.rb
+++ b/lib/prometheus_exporter/ext/metric/type_registry.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require 'prometheus_exporter/metric'
-require 'prometheus_exporter/ext/metric/gauge_with_time'
+require_relative 'gauge_with_time'
 
 module PrometheusExporter::Ext::Metric
   module TypeRegistry