diff --git a/web/plugins/perfometer/nfsiostat.py b/web/plugins/perfometer/nfsiostat.py
index 323fd5a..f791c3c 100644
--- a/web/plugins/perfometer/nfsiostat.py
+++ b/web/plugins/perfometer/nfsiostat.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python
 
 def perfometer_nfsiostat(row, check_command, perf_data):
+    if len(perf_data) < 2:
+        return "", ""
     for pd in perf_data:
         if pd[0] == u'op_s':
             ops = float(pd[1])