diff --git a/ds_test.go b/ds_test.go
index 9a57eac..727ab56 100644
--- a/ds_test.go
+++ b/ds_test.go
@@ -290,6 +290,9 @@ func TestDiskUsage(t *testing.T) {
 	}
 
 	du2, err := d.DiskUsage()
+	if err != nil {
+		t.Fatal(err)
+	}
 	if du2 <= du {
 		t.Fatal("size should have increased")
 	}