diff --git a/bin/logtool b/bin/logtool
index 5734bfc9ffffc5b6f8ba96dbd8caa1c5a932837d..721b0572fb0372d80a546574d12413d90d8e474e 100755
--- a/bin/logtool
+++ b/bin/logtool
@@ -66,7 +66,7 @@ following:
     styles = [
             Record(dashes=dashes, color=color)
             for dashes, color in cartesian_product(
-                [(), (12, 2), (4, 2),  (2,2) ],
+                [(), (12, 2), (4, 2),  (2,2), (2,8) ],
                 ["blue", "green", "red", "magenta", "cyan"],
                 )]
 
diff --git a/src/log.py b/src/log.py
index 8f30bc2c87c937a063f68a03d8f29ad96119c3ee..ea2492eea9a2a3699031666052838361ce732012 100644
--- a/src/log.py
+++ b/src/log.py
@@ -559,7 +559,12 @@ class LogManager(object):
 
         stepless_data = [tup for step, tup in data]
 
-        data_x, data_y = zip(*stepless_data)
+        if stepless_data:
+            data_x, data_y = zip(*stepless_data)
+        else:
+            data_x = []
+            data_y = []
+
         return (data_x, descr_x, unit_x), \
                (data_y, descr_y, unit_y)