diff --git a/cmd/syncthing/gui.go b/cmd/syncthing/gui.go
index 4b50a21ad..bf2e33fd2 100644
--- a/cmd/syncthing/gui.go
+++ b/cmd/syncthing/gui.go
@@ -848,8 +848,9 @@ func (s *apiService) flushResponse(resp string, w http.ResponseWriter) {
 }
 
 // 10 second average. Magic alpha value comes from looking at EWMA package
-// definitions of EWMA1, EWMA5.
-var cpuTickRate = 2 * time.Second
+// definitions of EWMA1, EWMA5. The tick rate *must* be five seconds (hard
+// coded in the EWMA package).
+var cpuTickRate = 5 * time.Second
 var cpuAverage = metrics.NewEWMA(1 - math.Exp(-float64(cpuTickRate)/float64(time.Second)/10.0))
 
 func init() {