diff --git a/docs/Makefile b/docs/Makefile
index c7e4c108..5be24dc2 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -5,6 +5,8 @@ default: book
 .PHONY: diagrams
 diagrams:
 	cd diagrams \
+		&& python3 -m venv .venv \
+		&& pip3 install -r requirements.txt \
 		&& python3 *.py
 
 .PHONY: book