diff --git a/Makefile b/Makefile
index 5aac9f38..54dc5e6f 100644
--- a/Makefile
+++ b/Makefile
@@ -107,3 +107,4 @@ clean:
 	rm -f ch07dry/datasource*.yaml
 	rm -f ch07dry/example.yaml
 	rm -f notebooks.zip
+	rm -rf contents