diff --git a/Makefile.config b/Makefile.config
index c01f960..281c110 100644
--- a/Makefile.config
+++ b/Makefile.config
@@ -10,8 +10,8 @@ BASE_FILENAME      := opensfx
 SOUND_FILE         := $(BASE_FILENAME).cat
 OBS_FILE           := $(BASE_FILENAME).obs
 
-SOUND_FILES        := $(ls src/wav/*.wav)
-LANG_FILES         := $(ls lang/*.lng)
+SOUND_FILES        := $(wildcard src/wav/*.wav)
+LANG_FILES         := $(wildcard lang/*.lng)
 
 BUNDLE_FILES        = $(BASE_FILENAME).obs $(DOC_FILES) $(SOUND_FILE)