diff --git a/src/lyx_main.C b/src/lyx_main.C
index 389647b562..27bfb44007 100644
--- a/src/lyx_main.C
+++ b/src/lyx_main.C
@@ -390,8 +390,9 @@ void LyX::prepareExit()
 		// FIXME UNICODE: package().temp_dir() could in theory contain utf8 characters.
 		// We cannot use from_utf8() here because this involves the use of static data
 		// that may have been destroyed already on Mac systems.
-		docstring const msg = _("Unable to remove the temporary directory") + " "
-			+ package().temp_dir().c_str();
+		docstring const msg =
+			bformat(_("Unable to remove the temporary directory %1$s"),
+			from_ascii(package().temp_dir()));
 		Alert::warning(_("Unable to remove temporary directory"), msg);
 	}
 }