diff --git a/var/spack/repos/builtin/packages/graphviz/package.py b/var/spack/repos/builtin/packages/graphviz/package.py
index a6aca843584..523aa49c7fd 100644
--- a/var/spack/repos/builtin/packages/graphviz/package.py
+++ b/var/spack/repos/builtin/packages/graphviz/package.py
@@ -117,6 +117,9 @@ class Graphviz(AutotoolsPackage):
     depends_on('bison', type='build')
     depends_on('flex', type='build')
     depends_on('libtool', type='build')
+    # required to build docs
+    depends_on('groff', type='build')
+    depends_on('ghostscript', type='build')
 
     parallel = False