diff --git a/packager/src/ModuleGraph/types.flow.js b/packager/src/ModuleGraph/types.flow.js
index 18def76ed59f27..aedf1e081be969 100644
--- a/packager/src/ModuleGraph/types.flow.js
+++ b/packager/src/ModuleGraph/types.flow.js
@@ -153,7 +153,7 @@ export type TransformedSourceFile =
 export type LibraryOptions = {|
   dependencies?: Array<string>,
   platform?: string,
-  root: string,
+  rebasePath: string => string,
 |};
 
 export type Base64Content = string;