diff --git a/docs/tools/requirements.txt b/docs/tools/requirements.txt
index d161ae22ebd..8414ae2c533 100644
--- a/docs/tools/requirements.txt
+++ b/docs/tools/requirements.txt
@@ -14,7 +14,6 @@ Jinja2==2.11.2
 jinja2-highlight==0.6.1
 jsmin==2.2.2
 livereload==2.6.1
-lunr==0.5.6
 Markdown==3.2.1
 MarkupSafe==1.1.1
 mkdocs==1.1