diff --git a/include/utils/BackupHelpers.h b/include/utils/BackupHelpers.h
index c78b99a..a21359f 100644
--- a/include/utils/BackupHelpers.h
+++ b/include/utils/BackupHelpers.h
@@ -71,6 +71,8 @@
     status_t WriteEntityHeader(const String8& key, size_t dataSize);
     status_t WriteEntityData(const void* data, size_t size);
 
+    void SetKeyPrefix(const String8& keyPrefix);
+
 private:
     explicit BackupDataWriter();
     status_t write_padding_for(int n);
@@ -79,6 +81,7 @@
     status_t m_status;
     ssize_t m_pos;
     int m_entityCount;
+    String8 m_keyPrefix;
 };
 
 /**