diff --git a/dashboard.py b/dashboard.py
index 6fea2f2..fd389c9 100644
--- a/dashboard.py
+++ b/dashboard.py
@@ -152,6 +152,8 @@ class TimeSeries(Widget):
         data = self.lts.data
         n = len(data)
         t_last = data[-1][0]
+        if len(data) < 5:
+            return "(not enough data)"
         dt = (t_last - data[-5][0]) / 4
         k = math.log((t_last - data[0][0]) / dt / n + 1)