diff --git a/admin/sync/themes.go b/admin/sync/themes.go
index 8623eccc..f3b9fb7f 100644
--- a/admin/sync/themes.go
+++ b/admin/sync/themes.go
@@ -97,6 +97,8 @@ func BuildTheme(i Importer, tdir string) (th *fic.Theme, errs []string) {
 		th.Image = path.Join(tdir, "heading.jpg")
 	} else if i.exists(path.Join(tdir, "heading.png")) {
 		th.Image = path.Join(tdir, "heading.png")
+	} else {
+		errs = append(errs, fmt.Sprintf("%q: heading.jpg: No such file", tdir))
 	}
 
 	return