diff --git a/sparklogstats/logparser.py b/sparklogstats/logparser.py
index 8900bc0..5c22a1b 100644
--- a/sparklogstats/logparser.py
+++ b/sparklogstats/logparser.py
@@ -209,7 +209,8 @@ def end(self):
 
     @property
     def bytes_read(self):
-        return sum(t.metrics.bytes_read for t in self.successful_tasks)
+        return sum(t.metrics.bytes_read for t in self.successful_tasks
+                   if t.metrics.bytes_read)
 
     @property
     def bytes_written(self):