diff --git a/.gitignore b/.gitignore
index a24b4731..ac4dec2e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,16 @@ tools/unit-test-app/sdkconfig
 tools/unit-test-app/sdkconfig.old
 tools/unit-test-app/build
 
+# Doc build artifacts
+docs/*/_build/
+docs/*/doxygen-warning-log.txt
+docs/*/sphinx-warning-log.txt
+docs/*/sphinx-warning-log-sanitized.txt
+docs/*/xml/
+docs/*/xml_in/
+docs/*/man/
+docs/doxygen_sqlite3.db
+
 # emacs
 .dir-locals.el
 
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 6a4de8f3..c495384e 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,12 +1,12 @@
 # This is a list of python packages used to generate documentation. This file is used with pip:
 # pip install --user -r requirements.txt
 #
-sphinx==1.6.5
+sphinx>=1.6.5
 sphinx-rtd-theme
-breathe==4.7.3
-sphinxcontrib-blockdiag==1.5.3
-sphinxcontrib-seqdiag==0.8.5
-sphinxcontrib-actdiag==0.8.5
-sphinxcontrib-nwdiag==0.9.5
+breathe>=4.7.3
+sphinxcontrib-blockdiag>=1.5.3
+sphinxcontrib-seqdiag>=0.8.5
+sphinxcontrib-actdiag>=0.8.5
+sphinxcontrib-nwdiag>=0.9.5
 recommonmark
 future>=0.16.0 # for ../tools/gen_esp_err_to_name.py