diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+* 0.1.2.1: 11 May 2012
+
+  - bump upper bound on containers to <0.6
+
 * 0.1.2: 22 December 2011
 
   - bump upper bound on base to compile under ghc 7.4
diff --git a/ottparse-pretty.cabal b/ottparse-pretty.cabal
--- a/ottparse-pretty.cabal
+++ b/ottparse-pretty.cabal
@@ -1,5 +1,5 @@
 Name:                ottparse-pretty
-Version:             0.1.2
+Version:             0.1.2.1
 Synopsis:            Pretty-printer for Ott parse trees
 Description:         Ott (<http://www.cl.cam.ac.uk/~pes20/ott/>) is a tool for
 		     writing formal definitions of programming
@@ -34,5 +34,5 @@
   Build-depends:     base >= 4.0 && < 4.6,
                      split >= 0.1 && < 0.2,
                      parsec >= 3.0 && < 3.2,
-                     containers >= 0.3 && < 0.5,
+                     containers >= 0.3 && < 0.6,
                      uniplate >= 1.6 && < 1.7