diff --git a/docs/requirements.txt b/docs/requirements.txt
index 162321c083..5b0b97b4c0 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -3,6 +3,7 @@
 #
 sphinx==2.3.1
 breathe==4.14.1
+sphinx-copybutton==0.3.0
 sphinx-notfound-page
 sphinxcontrib-blockdiag==2.0.0
 sphinxcontrib-seqdiag==2.0.0