diff --git a/Control/Monad/Reader/Trie.hs b/Control/Monad/Reader/Trie.hs
--- a/Control/Monad/Reader/Trie.hs
+++ b/Control/Monad/Reader/Trie.hs
@@ -71,6 +71,9 @@
 instance (HasTrie a, Indexable m) => Indexable (ReaderTrieT a m) where
   index = uncurry . fmap index . untrie . runReaderTrieT
 
+instance (HasTrie a, Adjustable m) => Adjustable (ReaderTrieT a m) where
+  adjust f (a,k) = ReaderTrieT . adjust (adjust f k) a . runReaderTrieT 
+
 instance (HasTrie a, Lookup ((:->:) a), Lookup m) => Lookup (ReaderTrieT a m) where
   lookup (k,k') (ReaderTrieT fm) = lookup k fm >>= lookup k'
 
diff --git a/Data/Functor/Representable/Trie.hs b/Data/Functor/Representable/Trie.hs
--- a/Data/Functor/Representable/Trie.hs
+++ b/Data/Functor/Representable/Trie.hs
@@ -55,7 +55,7 @@
 import Data.Traversable
 import Prelude hiding (lookup, foldr)
 
-class (TraversableWithKey1 (BaseTrie a), Representable (BaseTrie a)) => HasTrie a where
+class (Adjustable (BaseTrie a), TraversableWithKey1 (BaseTrie a), Representable (BaseTrie a)) => HasTrie a where
   type BaseTrie a :: * -> *
   -- projectKey . embedKey = id
   embedKey   :: a -> Key (BaseTrie a)
@@ -144,6 +144,9 @@
 
 instance HasTrie e => Representable ((:->:) e) where
   tabulate f = Trie $ tabulate (f . projectKey)
+
+instance HasTrie e => Adjustable ((:->:) e) where
+  adjust f k (Trie as) = Trie (adjust f (embedKey k) as)
 
 instance HasTrie e => Adjunction (Entry e) ((:->:) e) where
   unit = mapWithKey Entry . pure
diff --git a/representable-tries.cabal b/representable-tries.cabal
--- a/representable-tries.cabal
+++ b/representable-tries.cabal
@@ -1,6 +1,6 @@
 name:          representable-tries
 category:      Data Structures, Functors, Monads, Comonads
-version:       0.3.6
+version:       0.3.7
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
@@ -26,9 +26,9 @@
     comonad-transformers >= 1.6.3 && < 1.7.0,
     containers >= 0.3 && < 0.5,
     distributive >= 0.2 && < 0.3,
-    keys >= 0.2.6 && < 0.3,
+    keys >= 0.2.7 && < 0.3,
     mtl >= 2.0.1.0 && < 2.1,
-    representable-functors >= 0.4.2 && < 0.5,
+    representable-functors >= 0.4.4 && < 0.5,
     semigroups >= 0.5 && < 0.6,
     semigroupoids >= 1.2.2 && < 1.3.0,
     streams >= 0.7.1 && < 0.8,