diff --git a/build/mobile/devicemanagerADB.py b/build/mobile/devicemanagerADB.py
index 32743a325adf..5b9b6f958e87 100644
--- a/build/mobile/devicemanagerADB.py
+++ b/build/mobile/devicemanagerADB.py
@@ -323,7 +323,8 @@ class DeviceManagerADB(DeviceManager):
       ret.append(f)
       line =  p.stderr.readline()
     #the last line is a summary
-    ret.pop(len(ret) - 1)
+    if (len(ret) > 0):
+      ret.pop()
     return ret