diff --git a/tools/releasetools/both_generator.py b/tools/releasetools/both_generator.py
index df2a659..c042ae6 100644
--- a/tools/releasetools/both_generator.py
+++ b/tools/releasetools/both_generator.py
@@ -55,6 +55,7 @@
   def SetPermissionsRecursive(self, *a): self._DoBoth("SetPermissionsRecursive", *a)
   def MakeSymlinks(self, *a): self._DoBoth("MakeSymlinks", *a)
   def AppendExtra(self, *a): self._DoBoth("AppendExtra", *a)
+  def UnmountAll(self, *a): self._DoBoth("UnmountAll", *a)
 
   def AddToZip(self, input_zip, output_zip, input_path=None):
     self._DoBoth("AddToZip", input_zip, output_zip, input_path)