diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.4.0.1
+
+- Fixed Bézier interpolation.
+
 ## 0.4
 
 ### Breaking changes
diff --git a/smoothie.cabal b/smoothie.cabal
--- a/smoothie.cabal
+++ b/smoothie.cabal
@@ -1,5 +1,5 @@
 name:                smoothie
-version:             0.4
+version:             0.4.0.1
 synopsis:            Smooth curves via several interpolation modes
 description:         This package exports several splines you can use
                      to interpolate points in between. It includes instances for
@@ -19,7 +19,6 @@
 data-files:  CHANGELOG.md
 
 library
-
   ghc-options:         -W -Wall -O2 -funbox-strict-fields
 
   default-extensions:  DeriveFoldable
diff --git a/src/Data/Spline/Key.hs b/src/Data/Spline/Key.hs
--- a/src/Data/Spline/Key.hs
+++ b/src/Data/Spline/Key.hs
@@ -121,10 +121,14 @@
                   -> a s
                   -> a s
                   -> a s
-interpolateBezier s k0 r0 l1 k1 = (u ^+^ v) ^* s
+interpolateBezier s k0 r0 l1 k1 =
+    k0 ^* ms3 ^+^ r0 ^* (3 * ms2 * s) ^+^ l1 ^* (3 * ms * s2) ^+^ k1 ^* s3
   where
-    u = k0 ^+^ (r0 ^-^ k0) ^* s
-    v = l1 ^+^ (k1 ^-^ l1) ^* s
+    ms = 1 - s
+    ms2 = ms * ms
+    ms3 = ms2 * ms
+    s2 = s * s
+    s3 = s2 * s
 
 -- |Normalize a sampling value by clamping and scaling it between two 'Key's.
 --