diff --git a/type_test.go b/type_test.go
index f3ee219..83fee7b 100644
--- a/type_test.go
+++ b/type_test.go
@@ -21,6 +21,7 @@ func TestDeterminateImageType(t *testing.T) {
 		{"test.jp2", MAGICK},
 		{"test.heic", HEIF},
 		{"test2.heic", HEIF},
+		{"C001.heic", HEIF},
 	}
 
 	for _, file := range files {