diff --git a/ext/prometheus-cpp-lite-1.0/core/include/prometheus/counter.h b/ext/prometheus-cpp-lite-1.0/core/include/prometheus/counter.h
index 35231888f..5d8053739 100644
--- a/ext/prometheus-cpp-lite-1.0/core/include/prometheus/counter.h
+++ b/ext/prometheus-cpp-lite-1.0/core/include/prometheus/counter.h
@@ -38,7 +38,8 @@ namespace prometheus {
     static const Metric::Type static_type = Metric::Type::Counter;
 
     Counter() : Metric (Metric::Type::Counter) {}  ///< \brief Create a counter that starts at 0.
-
+    Counter(const Counter<Value_> &rhs) : Metric(static_type), value{rhs.value.load()} {}
+    
     // original API
 
     void Increment() { ///< \brief Increment the counter by 1.
diff --git a/ext/prometheus-cpp-lite-1.0/core/include/prometheus/gauge.h b/ext/prometheus-cpp-lite-1.0/core/include/prometheus/gauge.h
index f42308526..fcda14631 100644
--- a/ext/prometheus-cpp-lite-1.0/core/include/prometheus/gauge.h
+++ b/ext/prometheus-cpp-lite-1.0/core/include/prometheus/gauge.h
@@ -38,6 +38,7 @@ namespace prometheus {
 
       Gauge()                   : Metric (static_type) {}                  ///< \brief Create a gauge that starts at 0.
       Gauge(const Value value_) : Metric(static_type), value{ value_ } {}  ///< \brief Create a gauge that starts at the given amount.
+      Gauge(const Gauge<Value_> &rhs) : Metric(rhs.static_type), value{rhs.value.load()} {}
 
       // original API
 
diff --git a/ext/prometheus-cpp-lite-1.0/core/include/prometheus/histogram.h b/ext/prometheus-cpp-lite-1.0/core/include/prometheus/histogram.h
index 03cf461ea..ac558fa21 100644
--- a/ext/prometheus-cpp-lite-1.0/core/include/prometheus/histogram.h
+++ b/ext/prometheus-cpp-lite-1.0/core/include/prometheus/histogram.h
@@ -27,7 +27,7 @@ namespace prometheus {
   /// The class is thread-safe. No concurrent call to any API of this type causes
   /// a data race.
   template <typename Value_ = uint64_t>
-  class Histogram : Metric {
+  class Histogram : public Metric {
 
       using BucketBoundaries = std::vector<Value_>;
 
@@ -105,7 +105,7 @@ namespace prometheus {
         auto cumulative_count = 0ULL;
         metric.histogram.bucket.reserve(bucket_counts_.size());
         for (std::size_t i{0}; i < bucket_counts_.size(); ++i) {
-          cumulative_count += static_cast<std::size_t>(bucket_counts_[i].Value());
+          cumulative_count += static_cast<std::size_t>(bucket_counts_[i].Get());
           auto bucket = ClientMetric::Bucket{};
           bucket.cumulative_count = cumulative_count;
           bucket.upper_bound = (i == bucket_boundaries_.size()