diff --git a/preprocess b/preprocess
index 0162b83..5fb25cf 100755
--- a/preprocess
+++ b/preprocess
@@ -10,7 +10,7 @@ function r() {
 function preprocess() {
 	file="$1"
 	out="$(dirname "$file")/$(basename "$file" mpl)"
-	r "$RUBY" mplex -rmpl "$file" -o "$out"
+	r "$RUBY" mplex -r"./mpl" "$file" -o "$out"
 	if [ "$?" != 0 ]; then
 		echo ""
 		echo "** preprocess failed **"