diff --git a/src/interfaces/metric.hpp b/src/interfaces/metric.hpp
index c40e960..c52dd45 100644
--- a/src/interfaces/metric.hpp
+++ b/src/interfaces/metric.hpp
@@ -19,7 +19,7 @@
 
     virtual void initialize() = 0;
     virtual void deinitialize() = 0;
-    virtual std::vector<MetricValue> getReadings() const = 0;
+    virtual const std::vector<MetricValue>& getUpdatedReadings() = 0;
     virtual LabeledMetricParameters dumpConfiguration() const = 0;
     virtual uint64_t sensorCount() const = 0;
     virtual void registerForUpdates(interfaces::MetricListener& listener) = 0;