diff --git a/numhask.cabal b/numhask.cabal
--- a/numhask.cabal
+++ b/numhask.cabal
@@ -1,5 +1,5 @@
 name: numhask
-version: 0.0.8
+version: 0.0.9
 synopsis:
   A numeric prelude
 description:
@@ -28,7 +28,6 @@
 extra-source-files:
   readme.md
   stack.yaml
-
 library
   default-language:
     Haskell2010
diff --git a/src/NumHask/Algebra/Metric.hs b/src/NumHask/Algebra/Metric.hs
--- a/src/NumHask/Algebra/Metric.hs
+++ b/src/NumHask/Algebra/Metric.hs
@@ -18,9 +18,7 @@
 import Data.Complex (Complex(..))
 
 -- | abs and signnum are warts on the standard 'Num' class, and are separated here to provide a cleaner structure.
-class ( AdditiveUnital a
-      , AdditiveGroup a
-      , MultiplicativeUnital a
+class ( MultiplicativeUnital a
       ) => Signed a where
     sign :: a -> a
     abs :: a -> a
diff --git a/src/NumHask/Examples.hs b/src/NumHask/Examples.hs
--- a/src/NumHask/Examples.hs
+++ b/src/NumHask/Examples.hs
@@ -51,7 +51,6 @@
 -- >>> 1 / (1::Int)
 -- ...
 -- ... No instance for (MultiplicativeGroup Int)
--- ... arising from a use of ‘/’
 -- ...
 --
 -- >>> 1 / fromIntegral (1::Int)
diff --git a/stack.yaml b/stack.yaml
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,1 +1,3 @@
-resolver: lts-8.23
+resolver: lts-8.24
+
+extra-deps: []