diff --git a/client/cros/power_utils.py b/client/cros/power_utils.py
index 8926669..17c89e6 100644
--- a/client/cros/power_utils.py
+++ b/client/cros/power_utils.py
@@ -783,6 +783,7 @@
             _init_counter: integer of initial value of residency counter.
             _keyvals: dictionary of keyvals
         """
+        self._psr_path = ''
         if os.path.exists(self._PSR_STATUS_FILE_X86):
             self._psr_path = self._PSR_STATUS_FILE_X86
             self._psr_parse_prefix = 'Performance_Counter:'