diff --git a/changelog.txt b/changelog.txt
--- a/changelog.txt
+++ b/changelog.txt
@@ -1,3 +1,6 @@
+0.5.0.1
+- Fix doctest include path.
+
 0.5.0
 - Replace calls to Prelude's `atan2` function with calls to the C math
   library in `ArcTan2` instances for `Float` and `Double`
diff --git a/spatial-math.cabal b/spatial-math.cabal
--- a/spatial-math.cabal
+++ b/spatial-math.cabal
@@ -1,5 +1,5 @@
 name:                spatial-math
-version:             0.5.0.0
+version:             0.5.0.1
 synopsis:            3d math including quaternions/euler angles/dcms and utility functions
 description:         This is a port of my 'mathlib' C library: `https://github.com/ghorn/mathlib`
 license:             BSD3
diff --git a/tests/doctests.hs b/tests/doctests.hs
--- a/tests/doctests.hs
+++ b/tests/doctests.hs
@@ -5,4 +5,4 @@
 import Test.DocTest
 
 main :: IO ()
-main = doctest ["src/Types.hs", "src/SpatialMath.hs"]
+main = doctest ["-isrc", "src/Types.hs", "src/SpatialMath.hs"]