diff --git a/doc/source/conf.py b/doc/source/conf.py
index 502a6148..c2418a34 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -48,7 +48,7 @@ class Mock(MagicMock):
             return Mock()
 
 MOCK_MODULES = ['scipy.linalg.blas', 'blas', 'scipy.optimize', 'scipy.optimize.linesearch', 'scipy.linalg', 'scipy', 'scipy.special', 'scipy.integrate', 'scipy.io', 'scipy.stats', 'GPy.util.choleskies_cython',
-                'sympy', 'sympy.utilities.iterables', 'sympy.utilities.lambdify', 'sympy.utilities', 'sympy.utilities.codegen', 'sympy.core.cache', 'sympy.core', 'sympy.parsing', 'sympy.parsing.sympy_parser'
+                'sympy', 'sympy.utilities.iterables', 'sympy.utilities.lambdify', 'sympy.utilities', 'sympy.utilities.codegen', 'sympy.core.cache', 'sympy.core', 'sympy.parsing', 'sympy.parsing.sympy_parser',
                 'nose', 'nose.tools']
 sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)