diff --git a/docs/requirements.txt b/docs/requirements.txt
index 93a1dd3..0567ca7 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -4,4 +4,5 @@ sphinx-hoverxref==1.3.0
 sphinx-lua==1.1.5
 sphinx-rtd-theme==1.3.0
 sphinx-toolbox==3.5.0
+sphinxcontrib-images==0.9.4
 sphinxcontrib-luadomain==1.1.2