diff --git a/docs/Makefile b/docs/Makefile
index 08a88da..0edad84 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -13,7 +13,7 @@
 GENERATED_DOCS = build_glossary.md
 
 serve: setup
-	gitbook serve
+	gitbook serve --port 4040
 
 build: setup
 	gitbook build