diff --git a/vendor/github.com/armon/go-metrics/inmem_endpoint.go b/vendor/github.com/armon/go-metrics/inmem_endpoint.go
index 504f1b3..5fac958 100644
--- a/vendor/github.com/armon/go-metrics/inmem_endpoint.go
+++ b/vendor/github.com/armon/go-metrics/inmem_endpoint.go
@@ -41,6 +41,16 @@
 	DisplayLabels map[string]string `json:"Labels"`
 }
 
+// deepCopy allocates a new instance of AggregateSample
+func (source *SampledValue) deepCopy() SampledValue {
+	dest := *source
+	if source.AggregateSample != nil {
+		dest.AggregateSample = &AggregateSample{}
+		*dest.AggregateSample = *source.AggregateSample
+	}
+	return dest
+}
+
 // DisplayMetrics returns a summary of the metrics from the most recent finished interval.
 func (i *InmemSink) DisplayMetrics(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
 	data := i.Data()
@@ -52,12 +62,15 @@
 		return nil, fmt.Errorf("no metric intervals have been initialized yet")
 	case n == 1:
 		// Show the current interval if it's all we have
-		interval = i.intervals[0]
+		interval = data[0]
 	default:
 		// Show the most recent finished interval if we have one
-		interval = i.intervals[n-2]
+		interval = data[n-2]
 	}
 
+	interval.RLock()
+	defer interval.RUnlock()
+
 	summary := MetricsSummary{
 		Timestamp: interval.Interval.Round(time.Second).UTC().String(),
 		Gauges:    make([]GaugeValue, 0, len(interval.Gauges)),