diff --git a/src/Data/String/Builder.hs b/src/Data/String/Builder.hs
--- a/src/Data/String/Builder.hs
+++ b/src/Data/String/Builder.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE GADTs #-}
+{-# LANGUAGE TypeFamilies #-}
 -- |
 -- The `build` function can be used to construct multi-line string literals in
 -- a monadic way:
diff --git a/stringbuilder.cabal b/stringbuilder.cabal
--- a/stringbuilder.cabal
+++ b/stringbuilder.cabal
@@ -1,6 +1,6 @@
 name:             stringbuilder
-version:          0.3.0
-synopsis:         A monadic builder for multi-line string literals
+version:          0.4.0
+synopsis:         A writer monad for multi-line string literals
 description:      <https://github.com/sol/stringbuilder#readme>
 category:         Testing
 license:          MIT
@@ -21,7 +21,7 @@
   hs-source-dirs:
       src
   build-depends:
-      base < 5
+      base == 4.*
   exposed-modules:
       Data.String.Builder