diff --git a/common/constants.h b/common/constants.h
index f9a43c6..25d587b 100644
--- a/common/constants.h
+++ b/common/constants.h
@@ -32,6 +32,9 @@
 // The location where we store the AU preferences (state etc).
 extern const char kPrefsSubDirectory[];
 
+// Path to the post install command, relative to the partition.
+extern const char kPostinstallDefaultScript[];
+
 // Path to the stateful partition on the root filesystem.
 extern const char kStatefulPartition[];