diff --git a/setup.py b/setup.py
index 3fb7b3b..675789f 100755
--- a/setup.py
+++ b/setup.py
@@ -163,7 +163,7 @@ setup(name='qpms',
             #'quaternion','spherical_functions',
             'sympy>=1.2', 'numpy>=1.2'],
         #dependency_links=['https://github.com/moble/quaternion/archive/v2.0.tar.gz','https://github.com/moble/spherical_functions/archive/master.zip'],
-        ext_modules=cythonize([qpms_c, cywaves, cytranslations, cytmatrices, cycommon, cyquaternions, cybspec, cymaterials, cyewaldtest], include_path=['qpms', 'amos'], gdb_debug=True),
+        ext_modules=cythonize([qpms_c, cywaves, cytranslations, cytmatrices, cycommon, cyquaternions, cybspec, cymaterials, cyewaldtest], include_path=['qpms', 'amos'], gdb_debug=True, language_level=3),
         cmdclass = {'build_ext': build_ext},
         zip_safe=False
         )