diff --git a/PKGBUILD b/PKGBUILD
index 63232cb..90b9fda 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -8,13 +8,19 @@ url="http://www.box2d.org/"
 license=('MIT')
 arch=('x86_64')
 depends=('gcc-libs')
-makedepends=('cmake' 'doxygen' 'ninja')
+makedepends=('cmake' 'doctest' 'doxygen' 'ninja')
 # We're going to this alternate fork until the patches are upstreamed.
 # See https://github.com/erincatto/box2d/issues/621
 #source=("$pkgname-$pkgver.tar.gz::https://github.com/erincatto/Box2D/archive/v${pkgver}.tar.gz"
 source=("$pkgname-$pkgver.tar.gz::https://github.com/erincatto/box2d/archive/v2.4.1.tar.gz")
 sha512sums=('d900f925b77906777719c91488bdc5e2df1ad1f4a8ca39a574229f5e57070e3a843bdd7530e817112605fde6d82145c872d8afdfc65b84531a73199098c81162')
 
+prepare() {
+  # Use system doctest
+  rm  $pkgname-$pkgver/unit-test/doctest.h
+  ln -s /usr/include/doctest/doctest.h $pkgname-$pkgver/unit-test/doctest.h
+}
+
 build() {
   cd $pkgname-$pkgver