diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index b1b3dc4..e31ab0b 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -442,6 +442,8 @@ struct iso_volume *iso_volume_new_with_root(const char *volume_id,
  */
 void iso_volume_free(struct iso_volume *volume);
 
+void iso_volset_ref(struct iso_volset *volset);
+
 /**
  * Free a set of data volumes.
  */
diff --git a/libisofs/volume.c b/libisofs/volume.c
index e35a9c3..0999347 100644
--- a/libisofs/volume.c
+++ b/libisofs/volume.c
@@ -25,6 +25,12 @@ iso_volset_new(struct iso_volume *vol, const char *id)
 	return volset;
 }
 
+void
+iso_volset_ref(struct iso_volset *volset)
+{
+	++volset->refcount;
+}
+
 void
 iso_volset_free(struct iso_volset *volset)
 {