diff --git a/README b/README
index a6a824e..aaf93bb 100644
--- a/README
+++ b/README
@@ -9,6 +9,40 @@ comments to describe what it's doing.
 There's also a tutorial called tutorial.pdf.
 
 -- Revision History --
+
+v0.5: A major release, that makes backwards incompatible changes to
+      the generated code for the C backend.
+
+      The intent is for this release to be the last API-breaking one
+      before 2.0.
+
+      IMPORTANT: This release includes backwards incompatibilities. In
+      order to use it, you will need to add hooks for message
+      passing. See the parts of the tutorial that deal with
+      Handle_Message and Send_Message for details. In addition, some
+      names generated by Smudge may have been changed. If you use
+      anything other than alphanumeric characters for the names of
+      your state machines and events, you will have to update your
+      C code.
+
+      Features: Adds message passing hooks for user code to queue
+      events. Most names are now prettier. Added memory management
+      hooks for freeing events.
+
+      Documentation: Updated the tutorial to include the new and
+      exciting features.
+
+      Architecture: Replaced monolithic C backend with SmudgeIR
+      intermediate representation.
+
+      Tickets:
+
+      20: Refactor C backend to simplify.
+      60: Duration is Complicated.
+      65: Standardize on a properly injective mangling scheme
+      13: Message Passing is Complicated.
+      68: Fix documentation.
+
 v0.4: A major release, that corrects some long-standing Smudge issues.
 
       IMPORTANT: This includes a backwards-incompatible rename:
@@ -16,7 +50,7 @@ v0.4: A major release, that corrects some long-standing Smudge issues.
                     printf_assert -> SMUDGE_panic_print
 
       Features: Added --strict flag which only allows functions for
-      one event type.  The prototype for panic_print is now generated.  
+      one event type.  The prototype for panic_print is now generated.!
       Added --namespace flag, with a default namespace of SMUDGE.
       Added --rename flag, which lets you rename symbols, e.g.:
         smudge --rename="@SMUDGE.@panic @assert"
diff --git a/smudge.cabal b/smudge.cabal
index db207a2..5e2719c 100644
--- a/smudge.cabal
+++ b/smudge.cabal
@@ -7,7 +7,7 @@ Name:                smudge
 -- The package version. See the Haskell package versioning policy
 -- (http://www.haskell.org/haskellwiki/Package_versioning_policy) for
 -- standards guiding when and how versions should be incremented.
-Version:             0.4
+Version:             0.5
 
 -- A short (one-line) description of the package.
 Synopsis:            A tool to interpret state machines and automatically generate documentation and implementation.