diff --git a/main.go b/main.go
index 7a1f795..5ec8724 100644
--- a/main.go
+++ b/main.go
@@ -47,7 +47,10 @@ func main() {
 		log.WithError(err).Fatal("Unable to setup new compiler")
 	}
 
+	c.DefineVariable("filename", "")
 	c.DefineVariable("filepath", "")
+	c.DefineVariable("extension", "")
+	c.DefineVariable("filetype", "")
 
 	loadRules(c)