diff --git a/lib/facts/blob-service.js b/lib/facts/blob-service.js
--- a/lib/facts/blob-service.js
+++ b/lib/facts/blob-service.js
@@ -1,7 +1,9 @@
 // @flow
 
+type BlobServicePath = '/blob/:blobHash' | '/blob';
+
 export type BlobServiceHTTPEndpoint = {
-  +path: string,
+  +path: BlobServicePath,
   +method: 'GET' | 'POST' | 'PUT' | 'DELETE',
 };