diff --git a/Utils.h b/Utils.h
index 40f4d0a..48d605a 100644
--- a/Utils.h
+++ b/Utils.h
@@ -130,6 +130,8 @@
 /* Checks if Android is running in QEMU */
 bool IsRunningInEmulator();
 
+status_t UnmountTree(const std::string& prefix);
+
 }  // namespace vold
 }  // namespace android