diff --git a/Cabal/Distribution/PackageDescription.hs b/Cabal/Distribution/PackageDescription.hs
index 8165e99b342709ea4a92794ff33d370d1dfa69e9..d1aaedcdb3cf26ee1e1fedf529485afd89410140 100644
--- a/Cabal/Distribution/PackageDescription.hs
+++ b/Cabal/Distribution/PackageDescription.hs
@@ -310,10 +310,7 @@ defaultRenaming :: ModuleRenaming
 defaultRenaming = ModuleRenaming True []
 
 lookupRenaming :: Package pkg => pkg -> Map PackageName ModuleRenaming -> ModuleRenaming
-lookupRenaming pkg rns =
-    Map.findWithDefault
-        (error ("lookupRenaming: missing renaming for " ++ display (packageName pkg)))
-        (packageName pkg) rns
+lookupRenaming = Map.findWithDefault defaultRenaming . packageName
 
 instance Binary ModuleRenaming where
 
@@ -441,7 +438,7 @@ instance Text ModuleReexport where
 
     parse = do
       mpkgname <- Parse.option Nothing $ do
-                    pkgname <- parse 
+                    pkgname <- parse
                     _       <- Parse.char ':'
                     return (Just pkgname)
       origname <- parse