diff --git a/Makefile b/Makefile
index 7716a544..df9d9691 100644
--- a/Makefile
+++ b/Makefile
@@ -2,16 +2,19 @@ PACKAGE_NAME = treestyletab
 
 all: xpi
 
-xpi:
+xpi: buildscript/makexpi.sh
 	cp buildscript/makexpi.sh ./
 	rm chrome.manifest
 	cp jar-chrome.manifest chrome.manifest
 	./makexpi.sh -n $(PACKAGE_NAME)
 	rm ./makexpi.sh
 
-omnixpi:
+omnixpi: buildscript/makexpi.sh
 	cp buildscript/makexpi.sh ./
 	rm chrome.manifest
 	cp omnixpi-chrome.manifest chrome.manifest
 	./makexpi.sh -n $(PACKAGE_NAME)
 	rm ./makexpi.sh -o
+
+buildscript/makexpi.sh:
+	git submodule update --init