diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,8 @@
+0.6.4 [2019.04.01]
+------------------
+* Use more conservative CPP to guard the backported `MonadFix` instance for
+  `ListT`.
+
 0.6.3 [2019.04.01]
 ------------------
 * Backport changes from `transformers-0.5.6.*`:
diff --git a/src/Control/Monad/Trans/Instances.hs b/src/Control/Monad/Trans/Instances.hs
--- a/src/Control/Monad/Trans/Instances.hs
+++ b/src/Control/Monad/Trans/Instances.hs
@@ -604,9 +604,7 @@
     Constant x <> Constant y = Constant (x Semigroup.<> y)
     {-# INLINE (<>) #-}
 # endif
-#endif
 
-#if !(MIN_VERSION_transformers(0,5,6))
 instance (MonadFix m) => MonadFix (ListT m) where
     mfix f = ListT $ mfix (runListT . f . head) >>= \ xs -> case xs of
         [] -> return []
diff --git a/transformers-compat.cabal b/transformers-compat.cabal
--- a/transformers-compat.cabal
+++ b/transformers-compat.cabal
@@ -1,6 +1,6 @@
 name:          transformers-compat
 category:      Compatibility
-version:       0.6.3
+version:       0.6.4
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE