diff --git a/setup.py b/setup.py
index 1ae4796..f2e94ed 100644
--- a/setup.py
+++ b/setup.py
@@ -33,7 +33,7 @@ def _get_long_description():
         'scipy >=1.0.0, <2',
     ],
     extras_require={
-        'docs': ['sphinx >=3.0.0, <6', 'matplotlib >=3.1', 'numpydoc', 'm2r2'],
+        'docs': ['sphinx >=3.0.0, <7', 'matplotlib >=3.1', 'numpydoc', 'm2r2'],
         'tests': ['pytest', 'coverage <8', 'pytest-cov', 'coveralls'],
     },
     package_data={"csaps": ["py.typed"]},