diff --git a/filetypes/filetypes.go b/filetypes/filetypes.go
index 29e2f70..499c189 100644
--- a/filetypes/filetypes.go
+++ b/filetypes/filetypes.go
@@ -8,6 +8,7 @@ import (
 
 type FileDescription struct {
 	TkType           tk.FileType
+	TkTypeName       string
 	MacExtensions    []string
 	IconFile         string
 	MIMETypes        []string
@@ -18,7 +19,7 @@ type FileDescription struct {
 
 var Valid = []FileDescription{
 	{
-		TkType:           tk.FileType{TypeName: "BMP", Extensions: []string{".bmp"}},
+		TkTypeName:       "BMP",
 		MacExtensions:    []string{"bmp", "BMP"},
 		IconFile:         "bmp.icns",
 		MIMETypes:        []string{"image/bmp"},
@@ -27,7 +28,7 @@ var Valid = []FileDescription{
 		ItemContentTypes: "com.microsoft.bmp",
 	},
 	{
-		TkType:           tk.FileType{TypeName: "JPEG", Extensions: []string{".jpg", ".jpeg"}},
+		TkTypeName:       "JPEG",
 		MacExtensions:    []string{"jpg", "JPG", "jpeg", "JPEG"},
 		IconFile:         "jpeg.icns",
 		MIMETypes:        []string{"image/jpeg"},
@@ -36,7 +37,7 @@ var Valid = []FileDescription{
 		ItemContentTypes: "public.jpeg",
 	},
 	{
-		TkType:           tk.FileType{TypeName: "GIF", Extensions: []string{".gif"}},
+		TkTypeName:       "GIF",
 		MacExtensions:    []string{"gif", "GIF"},
 		IconFile:         "gif.icns",
 		MIMETypes:        []string{"image/gif"},
@@ -45,7 +46,7 @@ var Valid = []FileDescription{
 		ItemContentTypes: "com.compuserve.gif",
 	},
 	{
-		TkType:           tk.FileType{TypeName: "PNG", Extensions: []string{".png"}},
+		TkTypeName:       "PNG",
 		MacExtensions:    []string{"PNG", "png"},
 		IconFile:         "png.icns",
 		MIMETypes:        []string{"image/png"},
@@ -54,7 +55,7 @@ var Valid = []FileDescription{
 		ItemContentTypes: "public.png",
 	},
 	{
-		TkType:           tk.FileType{TypeName: "TGA", Extensions: []string{".tga"}},
+		TkTypeName:       "TGA",
 		MacExtensions:    []string{"tga", "TGA"},
 		IconFile:         "tga.icns",
 		MIMETypes:        []string{"image/targa", "image/tga", "application/tga"},
@@ -63,7 +64,7 @@ var Valid = []FileDescription{
 		ItemContentTypes: "com.truevision.tga-image",
 	},
 	{
-		TkType:           tk.FileType{TypeName: "TIFF", Extensions: []string{".tiff"}},
+		TkTypeName:       "TIFF",
 		MacExtensions:    []string{"tiff", "TIFF", "tif", "TIF"},
 		IconFile:         "tiff.icns",
 		MIMETypes:        []string{"image/tiff"},
@@ -76,7 +77,13 @@ var Valid = []FileDescription{
 func GetTkTypes(fds []FileDescription) []tk.FileType {
 	fts := make([]tk.FileType, len(fds))
 	for i, fd := range fds {
-		fts[i] = fd.TkType
+		fts[i] = tk.FileType{
+			TypeName:   fd.TkTypeName,
+			Extensions: make([]string, len(fd.MacExtensions)),
+		}
+		for j, ex := range fd.MacExtensions {
+			fts[i].Extensions[j] = fmt.Sprintf(".%s", ex)
+		}
 	}
 	return fts
 }
diff --git a/main.go b/main.go
index 0eb00e2..f524ec3 100644
--- a/main.go
+++ b/main.go
@@ -49,8 +49,11 @@ func isImage(entry os.DirEntry) bool {
 		return false
 	}
 	ext := filepath.Ext(entry.Name())
+	if ext == "" {
+		return false
+	}
 	for _, ft := range validFileTypes {
-		if slices.Contains(ft.TkType.Extensions, ext) {
+		if slices.Contains(ft.MacExtensions, ext[1:]) {
 			return true
 		}
 	}