diff --git a/lib/spack/docs/build_systems/cudapackage.rst b/lib/spack/docs/build_systems/cudapackage.rst
index 2d148d0483..119d296ced 100644
--- a/lib/spack/docs/build_systems/cudapackage.rst
+++ b/lib/spack/docs/build_systems/cudapackage.rst
@@ -10,7 +10,7 @@ CudaPackage
 -----------
 
 Different from other packages, ``CudaPackage`` does not represent a build system.
-Instead its goal is to simplify and unify usage of ``CUDA`` in other packages by providing a ` mixin-class <https://en.wikipedia.org/wiki/Mixin>`__.
+Instead its goal is to simplify and unify usage of ``CUDA`` in other packages by providing a `mixin-class <https://en.wikipedia.org/wiki/Mixin>`_.
 
 You can find source for the package at
 `<https://github.com/spack/spack/blob/develop/lib/spack/spack/build_systems/cuda.py>`__.