diff --git a/src/Stylist/Tree.hs b/src/Stylist/Tree.hs
--- a/src/Stylist/Tree.hs
+++ b/src/Stylist/Tree.hs
@@ -8,7 +8,7 @@
 data StyleTree p = StyleTree {
     style :: p,
     children :: [StyleTree p]
-}
+} deriving (Read, Show, Eq, Ord)
 
 -- | Indices within the tree.
 type Path = [Integer]
diff --git a/stylist-traits.cabal b/stylist-traits.cabal
--- a/stylist-traits.cabal
+++ b/stylist-traits.cabal
@@ -10,7 +10,7 @@
 -- PVP summary:      +-+------- breaking API changes
 --                   | | +----- non-breaking API additions
 --                   | | | +--- code changes with no API change
-version:             0.1.3.1
+version:             0.1.4.0
 
 -- A short (one-line) description of the package.
 synopsis:            Traits, datatypes, & parsers for Haskell Stylist
@@ -65,7 +65,7 @@
   -- other-extensions:
 
   -- Other library packages from which modules are imported.
-  build-depends:       base >=4.12 && <4.16, css-syntax >=0.1 && <0.2, text, network-uri >= 2.6 && <2.7
+  build-depends:       base >=4.12 && <5, css-syntax >=0.1 && <0.2, text, network-uri >= 2.6 && <2.7
 
   -- Directories containing source files.
   hs-source-dirs:      src