diff --git a/setup.py b/setup.py
index 1fc7ea5..598643b 100644
--- a/setup.py
+++ b/setup.py
@@ -288,9 +288,9 @@
             "doc8",
             "pyenchant >= 1.6.11",
             "readme_renderer >= 16.0",
-            "sphinx",
+            "sphinx >= 1.6.5",
             "sphinx_rtd_theme",
-            "sphinxcontrib-spelling",
+            "sphinxcontrib-spelling >= 4.0.1",
         ],
         "pep8test": [
             "flake8",