diff --git a/sprite_cut/test.gd b/sprite_cut/test.gd
new file mode 100644
index 0000000..e69de29
diff --git a/src/gontage.go b/src/gontage.go
index d96665e..a77d274 100644
--- a/src/gontage.go
+++ b/src/gontage.go
@@ -106,7 +106,7 @@ func decodeImages(sprites_folder []fs.DirEntry, targetFolder string, pwd string,
 	var sprites_array []image.Image
 	var sprites_names []string
 	for _, sprite := range sprites_folder {
-		if !sprite.IsDir() {
+		if !sprite.IsDir() && filepath.Ext(sprite.Name()) == ".png" {
 			if reader, err := os.Open(filepath.Join(pwd, targetFolder, sprite.Name())); err == nil {
 				m, _, err := image.Decode(reader)
 				if err != nil {