diff --git a/ltsdb_json.py b/ltsdb_json.py
index 4537dcb..b70a3b5 100644
--- a/ltsdb_json.py
+++ b/ltsdb_json.py
@@ -54,7 +54,8 @@ class LTS:
         data = self.data
         n = len(data)
         t_last = data[-1][0]
-        dt = (t_last - data[-5][0]) / 4
+        dt = max((t_last - data[-5][0]) / 4, 1)
+        log.debug("dt = %s, n = %s", dt, n)
         k = math.log((t_last - data[0][0]) / dt / n + 1)
         for i in range(1, n):
             t_ideal = (math.exp(k * (n - i)/n) - 1) * (n * dt)