diff --git a/devlib/instrument/frames.py b/devlib/instrument/frames.py
index 62fcc75..e9c929e 100644
--- a/devlib/instrument/frames.py
+++ b/devlib/instrument/frames.py
@@ -14,6 +14,8 @@
 #
 
 from __future__ import division
+import os
+
 from devlib.instrument import (Instrument, CONTINUOUS,
                                MeasurementsCsv, MeasurementType)
 from devlib.utils.rendering import (GfxinfoFrameCollector,