diff --git a/mono-traversable.cabal b/mono-traversable.cabal
--- a/mono-traversable.cabal
+++ b/mono-traversable.cabal
@@ -1,5 +1,5 @@
 name:                mono-traversable
-version:             0.6.0.3
+version:             0.6.0.4
 synopsis:            Type classes for mapping, folding, and traversing monomorphic containers
 description:         Monomorphic variants of the Functor, Foldable, and Traversable typeclasses. Contains even more experimental code for abstracting containers and sequences.
 homepage:            https://github.com/snoyberg/mono-traversable
diff --git a/src/Data/Containers.hs b/src/Data/Containers.hs
--- a/src/Data/Containers.hs
+++ b/src/Data/Containers.hs
@@ -10,8 +10,10 @@
 import Data.Maybe (fromMaybe)
 #if MIN_VERSION_containers(0, 5, 0)
 import qualified Data.Map.Strict as Map
+import qualified Data.IntMap.Strict as IntMap
 #else
 import qualified Data.Map as Map
+import qualified Data.IntMap as IntMap
 #endif
 import qualified Data.HashMap.Strict as HashMap
 import Data.Hashable (Hashable)
@@ -20,7 +22,6 @@
 import Data.Monoid (Monoid (..))
 import Data.Semigroup (Semigroup)
 import Data.MonoTraversable (MonoFunctor(..), MonoFoldable, MonoTraversable, Element)
-import qualified Data.IntMap as IntMap
 import Data.Function (on)
 import qualified Data.List as List
 import qualified Data.IntSet as IntSet
@@ -39,6 +40,10 @@
     union :: set -> set -> set
     difference :: set -> set -> set
     intersection :: set -> set -> set
+
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.Map.Strict".
+#endif
 instance Ord k => SetContainer (Map.Map k v) where
     type ContainerKey (Map.Map k v) = k
     member = Map.member
@@ -52,6 +57,9 @@
     intersection = Map.intersection
     {-# INLINE intersection #-}
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.HashMap.Strict".
+#endif
 instance (Eq key, Hashable key) => SetContainer (HashMap.HashMap key value) where
     type ContainerKey (HashMap.HashMap key value) = key
     member = HashMap.member
@@ -65,6 +73,9 @@
     intersection = HashMap.intersection
     {-# INLINE intersection #-}
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.IntMap.Strict".
+#endif
 instance SetContainer (IntMap.IntMap value) where
     type ContainerKey (IntMap.IntMap value) = Int
     member = IntMap.member
@@ -148,6 +159,9 @@
     intersectionWithMap :: (value1 -> value2 -> value3)
                         -> map value1 -> map value2 -> map value3
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.Map.Strict".
+#endif
 instance Ord key => PolyMap (Map.Map key) where
     differenceMap = Map.difference
     {-# INLINE differenceMap #-}
@@ -157,6 +171,9 @@
     intersectionWithMap = Map.intersectionWith
     {-# INLINE intersectionWithMap #-}
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.HashMap.Strict".
+#endif
 instance (Eq key, Hashable key) => PolyMap (HashMap.HashMap key) where
     differenceMap = HashMap.difference
     {-# INLINE differenceMap #-}
@@ -166,6 +183,9 @@
     intersectionWithMap = HashMap.intersectionWith
     {-# INLINE intersectionWithMap #-}
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.IntMap.Strict".
+#endif
 instance PolyMap IntMap.IntMap where
     differenceMap = IntMap.difference
     {-# INLINE differenceMap #-}
@@ -363,6 +383,9 @@
       where
         go (k, v) = [(f k, v)]
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.Map.Strict".
+#endif
 instance Ord key => IsMap (Map.Map key value) where
     type MapValue (Map.Map key value) = value
     lookup = Map.lookup
@@ -409,6 +432,9 @@
     mapKeysWith = Map.mapKeysWith
     {-# INLINE mapKeysWith #-}
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.HashMap.Strict".
+#endif
 instance (Eq key, Hashable key) => IsMap (HashMap.HashMap key value) where
     type MapValue (HashMap.HashMap key value) = value
     lookup = HashMap.lookup
@@ -443,6 +469,9 @@
     --mapWithKey = HashMap.mapWithKey
     --mapKeysWith = HashMap.mapKeysWith
 
+#if MIN_VERSION_containers(0, 5, 0)
+-- | This instance uses the functions from "Data.IntMap.Strict".
+#endif
 instance IsMap (IntMap.IntMap value) where
     type MapValue (IntMap.IntMap value) = value
     lookup = IntMap.lookup