diff --git a/speedtest.py b/speedtest.py
index 92a2be0..1d9a234 100755
--- a/speedtest.py
+++ b/speedtest.py
@@ -1567,7 +1567,7 @@ class Speedtest(object):
             cons_thread.join(timeout=0.001)
 
         stop = timeit.default_timer()
-        self.results.bytes_received = sum(finished)
+        self.results.bytes_received = sum(filter(None, finished))
         self.results.download = (
             (self.results.bytes_received / (stop - start)) * 8.0
         )
@@ -1661,7 +1661,7 @@ class Speedtest(object):
             cons_thread.join(timeout=0.1)
 
         stop = timeit.default_timer()
-        self.results.bytes_sent = sum(finished)
+        self.results.bytes_sent = sum(filter(None, finished))
         self.results.upload = (
             (self.results.bytes_sent / (stop - start)) * 8.0
         )