diff --git a/book_include.ly b/book_include.ly
index ea87159..9832013 100644
--- a/book_include.ly
+++ b/book_include.ly
@@ -9,7 +9,7 @@
     	     (closedir dir)
     	     files)
     	    (else
-    	     (next (readdir dir) (if (string-match "^(0|\\.)" f) files (cons f files))))))))
+    	     (next (readdir dir) (if (ly:regex-match? (ly:regex-exec (ly:make-regex "^(0|\\.)") f)) files (cons f files))))))))
 
 #(define (file-to-stats filename)
    (set! song-list (cons filename song-list)))