diff --git a/Makefile b/Makefile
index b4e01dd5e9d96f54d28b82fee4a2510355609971..c15e99fd01430808502712c8adae004e6723f057 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 out_dir = temp
 
-Conversion.jar: src/inport/*.java src/constraints/*.mzn manifest.txt
+Conversion.jar: src/inport/**/*.java src/constraints/*.mzn
 	mkdir -p $(out_dir)
-	javac -d $(out_dir) -encoding UTF-8 -classpath annotations-java8.jar src/inport/*.java
-	cd $(out_dir) && jar -cvfm ../Conversion.jar ../manifest.txt inport/* ../src/constraints/../constraints/*
+	javac -d $(out_dir) -encoding UTF-8 -classpath annotations-java8.jar src/inport/*.java src/inport/ConversionUtils/*.java
+	jar cfe Conversion.jar inport.Main -C $(out_dir) inport -C src constraints
+	rm -r -f $(out_dir)