diff --git a/server/metrics/metrics.go b/server/metrics/metrics.go
index abbcac4..805515a 100644
--- a/server/metrics/metrics.go
+++ b/server/metrics/metrics.go
@@ -151,11 +151,13 @@ func (mh *monitorHistory) Months() []float64 {
 }
 
 func (mh *monitorHistory) Report(w *bufio.Writer) {
+	mh.lock.Lock()
 	fmt.Fprintln(w, "Minutes:", reportLine(mh.monitorType, mh.perMinutePerHour[:]))
 	fmt.Fprintln(w, "Hours:  ", reportLine(mh.monitorType, mh.perHourForDay[:]))
 	fmt.Fprintln(w, "Days:   ", reportLine(mh.monitorType, mh.perDayForWeek[:]))
 	fmt.Fprintln(w, "Weeks:  ", reportLine(mh.monitorType, mh.perWeekForMonth[:]))
 	fmt.Fprintln(w, "Months: ", reportLine(mh.monitorType, mh.perMonthForYear[:]))
+	mh.lock.Unlock()
 }
 
 func reportLine(t MonitorType, array []float64) string {