diff --git a/colour-space.cabal b/colour-space.cabal
--- a/colour-space.cabal
+++ b/colour-space.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                colour-space
-version:             0.1.2.0
+version:             0.1.3.0
 synopsis:            Instances of the manifold-classes for colour types
 -- description:         
 homepage:            https://github.com/leftaroundabout/colour-space
@@ -21,7 +21,7 @@
   -- other-modules:       
   -- other-extensions:    
   build-depends:       base >=4.7 && <5
-                     , manifolds >=0.3.1 && <0.4
+                     , manifolds >=0.4.1 && <0.5
                      , constrained-categories
                      , linearmap-category
                      , linear
diff --git a/src/Data/Colour/Manifold.hs b/src/Data/Colour/Manifold.hs
--- a/src/Data/Colour/Manifold.hs
+++ b/src/Data/Colour/Manifold.hs
@@ -7,6 +7,7 @@
 
 module Data.Colour.Manifold (Colour, QuantisedColour(..)) where
 
+import Data.Functor (($>))
 import Control.Applicative (empty)
 import Control.Applicative.Constrained
 import Control.Arrow.Constrained
@@ -14,6 +15,7 @@
 
 import Data.Manifold.PseudoAffine
 import Data.Manifold.Types
+import Data.Manifold.Atlas
 import Data.Manifold.Riemannian
 import Data.VectorSpace
 import Data.AffineSpace
@@ -22,6 +24,7 @@
 import Data.Colour.SRGB (toSRGB, toSRGB24)
 import Data.Colour.SRGB.Linear
 import Data.Colour hiding (AffineSpace)
+import Data.Colour.Names
 
 import Math.LinearMap.Category
 import Linear.V3
@@ -34,7 +37,7 @@
 import Data.Coerce
 import Data.Type.Coercion
 
-newtype ColourNeedle = ColourNeedle { getRGBNeedle :: RGB ℝ } deriving (Show)
+newtype ColourNeedle = ColourNeedle { getRGBNeedle :: RGB ℝ } deriving (Eq, Show)
 
 asV3Needle :: ColourNeedle -+> V3 ℝ
 asV3Needle = LinearFunction $ \(ColourNeedle (RGB r g b)) -> V3 r g b
@@ -84,6 +87,8 @@
   fzipTensorWith = bilinearFunction $ \f (Tensor (RGB r g b), Tensor (RGB r' g' b'))
                    -> Tensor $ RGB (f $ (r,r')) (f $ (g,g')) (f $ (b,b'))
   coerceFmapTensorProduct _ Coercion = Coercion
+  wellDefinedTensor t@(Tensor (RGB r g b))
+    = wellDefinedVector r >> wellDefinedVector g >> wellDefinedVector b $> t
 
 instance LinearSpace ColourNeedle where
   type DualVector ColourNeedle = ColourNeedle
@@ -194,6 +199,11 @@
 instance PseudoAffine ColourNeedle where
   ColourNeedle q .-~. ColourNeedle s = pure . ColourNeedle $ liftA2 (-) q s
 
+instance Atlas ColourNeedle where
+  type ChartIndex ColourNeedle = ()
+  interiorChartReferencePoint _ () = zeroV
+  lookupAtlas _ = ()
+
 instance AffineSpace ColourNeedle where
   type Diff ColourNeedle = ColourNeedle
   (.-.) = (.-~!)
@@ -247,6 +257,13 @@
                                         $ RGB (lerp r r' η')
                                               (lerp g g' η')
                                               (lerp b b' η')
+
+instance Atlas (Colour ℝ) where
+  type ChartIndex (Colour ℝ) = ()
+  chartReferencePoint () = grey
+  interiorChartReferencePoint = \_ () -> intGrey
+   where Just intGrey = toInterior (grey :: Colour ℝ)
+  lookupAtlas _ = ()
 
 class QuantisedColour c where
   quantiseColour :: Colour ℝ -> c