diff --git a/riak.cabal b/riak.cabal
--- a/riak.cabal
+++ b/riak.cabal
@@ -1,5 +1,5 @@
 name:                riak
-version:             0.6.0.0
+version:             0.6.0.1
 synopsis:            A Haskell client for the Riak decentralized data store
 description:
   A Haskell client library for the Riak decentralized data
diff --git a/src/Network/Riak/Escape.hs b/src/Network/Riak/Escape.hs
--- a/src/Network/Riak/Escape.hs
+++ b/src/Network/Riak/Escape.hs
@@ -100,7 +100,7 @@
     | otherwise = acc `mappend` hex i
   where
     literal w = w >= 97 && w <= 122 || w >= 65 && w <= 90 ||
-                w >= 48 && w <= 57 || w `B.elem` "$-.!*'(),"
+                w >= 48 && w <= 57 || w `B.elem` "$-.!*'(),_"
     hex w = fromWord8 37 `mappend` d (w `shiftR` 4) `mappend` d (w .&. 0xf)
     d n | n < 10    = fromWord8 (n + 48)
         | otherwise = fromWord8 (n + 87)