diff --git a/DOC/requirements.txt b/DOC/requirements.txt
index 46beeb9..0d6c023 100644
--- a/DOC/requirements.txt
+++ b/DOC/requirements.txt
@@ -7,6 +7,7 @@
 
 #Handle references in bibtex format
 sphinxcontrib-bibtex
+sphinxcontrib-tikz
 
 #Work-around bug "AttributeError: 'Values' object has no attribute 'character_level_inline_markup'" with docutils 0.13.1
 #See: