diff --git a/common/flatpak-installed-ref.c b/common/flatpak-installed-ref.c
index 528a51f50..38ad0929c 100644
--- a/common/flatpak-installed-ref.c
+++ b/common/flatpak-installed-ref.c
@@ -280,7 +280,7 @@ flatpak_installed_ref_get_origin (FlatpakInstalledRef *self)
  *
  * Gets the latest commit of the ref.
  *
- * Returns: (transfer none): the latest commit
+ * Returns: (transfer none) (nullable): the latest commit
  */
 const char *
 flatpak_installed_ref_get_latest_commit (FlatpakInstalledRef *self)