diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+0.3.1 Enzo Haussecker <enzo@dfinity.org> Mon Aug 06 2018
+
+ *  Relax constraint on radix database instance
+
 0.3.0 Enzo Haussecker <enzo@dfinity.org> Thu Aug 02 2018
 
  * Add thread safety to parallel download combinators
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -13,12 +13,12 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 
-import Control.Monad.Trans.Resource (MonadResource)
+import Control.Monad.IO.Class (MonadIO)
 import Database.LevelDB (DB, defaultReadOptions, defaultWriteOptions, get, put)
 
 import Network.DFINITY.RadixTree
 
-instance MonadResource m => RadixDatabase m DB where
+instance MonadIO m => RadixDatabase m DB where
    load database = get database defaultReadOptions
    store database = put database defaultWriteOptions
 ```
diff --git a/dfinity-radix-tree.cabal b/dfinity-radix-tree.cabal
--- a/dfinity-radix-tree.cabal
+++ b/dfinity-radix-tree.cabal
@@ -1,5 +1,5 @@
 Name:               dfinity-radix-tree
-Version:            0.3.0
+Version:            0.3.1
 Synopsis:           A generic data integrity layer.
 Description:
    This library allows you to construct a Merkle tree on top of any underlying
diff --git a/src/Network/DFINITY/RadixTree/Types.hs b/src/Network/DFINITY/RadixTree/Types.hs
--- a/src/Network/DFINITY/RadixTree/Types.hs
+++ b/src/Network/DFINITY/RadixTree/Types.hs
@@ -26,8 +26,8 @@
 import Control.DeepSeq (NFData(..))
 import Control.Exception (Exception)
 import Control.Monad (void)
+import Control.Monad.IO.Class
 import Control.Monad.State.Strict as State (StateT, get, modify)
-import Control.Monad.Trans.Resource (MonadResource)
 import Crypto.Hash.SHA256 (hash)
 import Data.BloomFilter (Bloom)
 import Data.Bool (bool)
@@ -64,7 +64,7 @@
    load _ key = Map.lookup key <$> State.get
    store _ key = modify . insert key
 
-instance MonadResource m => RadixDatabase m DB where
+instance MonadIO m => RadixDatabase m DB where
    load database = LevelDB.get database defaultReadOptions
    store database = put database defaultWriteOptions