2 files changed, 8 insertions, 3 deletions
diff --git a/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs b/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
index f54b7c22..176180ad 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
@@ -31,6 +31,7 @@ import Haddock.Doc (combineDocumentation)
 
 import           Data.List             ( intersperse, sort )
 import qualified Data.Map as Map
+import qualified Data.Set as Set
 import           Data.Maybe
 import           Text.XHtml hiding     ( name, title, p, quote )
 
@@ -540,9 +541,12 @@ ppInstanceSigs :: LinksInfo -> Splice -> Unicode -> Qualification
 ppInstanceSigs links splice unicode qual (InstSpec {..}) (InstHead {..}) = do
     TypeSig lnames (L sspan typ) _ <- ispecSigs
     let names = map unLoc lnames
-    let typ' = sugar $ specializeTyVarBndrs ispecTyVars ihdTypes typ
+    let typ' = rename' . sugar $ specializeTyVarBndrs ispecTyVars ihdTypes typ
     return $ ppFunSig False links sspan noDocForDecl names typ' []
         splice unicode qual
+  where
+    fv = foldr Set.union Set.empty . map freeVariables $ ihdTypes
+    rename' = rename fv
 
 
 lookupAnySubdoc :: Eq id1 => id1 -> [(id1, DocForDecl id2)] -> DocForDecl id2
diff --git a/haddock-api/src/Haddock/Backends/Xhtml/Specialize.hs b/haddock-api/src/Haddock/Backends/Xhtml/Specialize.hs
index 4e68cb7b..3b3d95b9 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml/Specialize.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml/Specialize.hs
@@ -7,6 +7,7 @@ module Haddock.Backends.Xhtml.Specialize
     ( specialize, specialize'
     , specializeTyVarBndrs
     , sugar, rename
+    , freeVariables
     ) where
 
 
@@ -111,8 +112,8 @@ setInternalOccName occ name =
     nname' = mkInternalName (nameUnique nname) occ (nameSrcSpan nname)
 
 
-rename :: SetName name => HsType name -> HsType name
-rename = fst . evalRWS undefined Map.empty . renameType -- TODO.
+rename :: SetName name => Set OccName -> HsType name -> HsType name
+rename fv typ = fst $ evalRWS (renameType typ) fv Map.empty
 
 
 type Rename name a = RWS (Set OccName) () (Map Name name) a