diff --git a/common/flatpak-dir.c b/common/flatpak-dir.c
index 1ff4218e..929063d1 100644
--- a/common/flatpak-dir.c
+++ b/common/flatpak-dir.c
@@ -17351,12 +17351,15 @@ static void
                      ...)
 {
 #ifdef HAVE_LIBSYSTEMD
-  const char *installation = source ? source : flatpak_dir_get_name_cached (self);
-  const char *subject = self->subject ? polkit_subject_to_string (self->subject) : "(none)";
+  const char *installation;
+  g_autofree char *subject = NULL;
   char message[1024];
   int len;
   va_list args;
 
+  installation = source ? source : flatpak_dir_get_name_cached (self);
+  subject = self->subject ? polkit_subject_to_string (self->subject) : g_strdup ("(none)");
+
   len = g_snprintf (message, sizeof (message), "%s: ", installation);
 
   va_start (args, format);