diff --git a/docs/requirements.txt b/docs/requirements.txt
index 85f30a2e..3c4674fd 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,3 +1,3 @@
-Sphinx==2.1.2
-sphinxcontrib-programoutput==0.14
-alabaster==0.7.10
+Sphinx==2.1.2; python_version > '3.0'
+sphinxcontrib-programoutput==0.14; python_version > '3.0'
+alabaster==0.7.10; python_version > '3.0'