diff --git a/internal/thumb/open_jpeg_test.go b/internal/thumb/open_jpeg_test.go
index cfa52fe22..15b7da38c 100644
--- a/internal/thumb/open_jpeg_test.go
+++ b/internal/thumb/open_jpeg_test.go
@@ -35,4 +35,11 @@ func TestOpenJpeg(t *testing.T) {
 			t.Error("img must not be nil")
 		}
 	})
+	t.Run("filename empty", func(t *testing.T) {
+		img, err := OpenJpeg("", 0)
+
+		assert.Error(t, err)
+		assert.Equal(t, "filename missing", err.Error())
+		assert.Nil(t, img)
+	})
 }
diff --git a/internal/thumb/quality_test.go b/internal/thumb/quality_test.go
index 4361e9f4f..ea1feef67 100644
--- a/internal/thumb/quality_test.go
+++ b/internal/thumb/quality_test.go
@@ -81,3 +81,10 @@ func TestParseQuality(t *testing.T) {
 		assert.Equal(t, Quality(100), ParseQuality("100"))
 	})
 }
+
+func TestQuality_String(t *testing.T) {
+	assert.Equal(t, "95", QualityBest.String())
+	assert.Equal(t, "92", QualityHigh.String())
+	assert.Equal(t, "75", QualityBad.String())
+
+}