diff --git a/python-lxml.spec b/python-lxml.spec
index d9a9406..3830094 100644
--- a/python-lxml.spec
+++ b/python-lxml.spec
@@ -54,6 +54,7 @@ Python 3 version.
 %autosetup -n %{modname}-%{version}
 
 %build
+export WITH_CYTHON=true
 %py2_build
 %py3_build