diff --git a/docs/requirements.txt b/docs/requirements.txt
index c1831dc05..b9c8bda87 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,3 +1,4 @@
 tox
 pyusb
+pyvcd
 sphinx_rtd_theme==1.3.0
\ No newline at end of file