diff --git a/ghc-mod.cabal b/ghc-mod.cabal
index 464353f..77b2983 100644
--- a/ghc-mod.cabal
+++ b/ghc-mod.cabal
@@ -46,6 +46,7 @@ Extra-Source-Files:     ChangeLog
                         test/data/ghc-mod-check/*.hs
                         test/data/ghc-mod-check/Data/*.hs
                         test/data/subdir1/subdir2/dummy
+                        test/data/.cabal-sandbox/packages/00-index.tar
 
 Library
   Default-Language:     Haskell2010