diff --git a/ceilometer/hardware/pollsters/system.py b/ceilometer/hardware/pollsters/system.py
index 9063a9d2e..2cfc696d8 100644
--- a/ceilometer/hardware/pollsters/system.py
+++ b/ceilometer/hardware/pollsters/system.py
@@ -40,11 +40,11 @@ class SystemCpuIdlePollster(_SystemBase):
 
 class SystemIORawSentPollster(_SystemBase):
     IDENTIFIER = 'system_stats.io.outgoing.blocks'
-    TYPE = sample.TYPE_CUMULATIVE,
+    TYPE = sample.TYPE_CUMULATIVE
     UNIT = 'blocks'
 
 
 class SystemIORawReceivedPollster(_SystemBase):
     IDENTIFIER = 'system_stats.io.incoming.blocks'
-    TYPE = sample.TYPE_CUMULATIVE,
+    TYPE = sample.TYPE_CUMULATIVE
     UNIT = 'blocks'