diff --git a/openbox/session.c b/openbox/session.c
index 8be44e34..651f1a90 100644
--- a/openbox/session.c
+++ b/openbox/session.c
@@ -318,6 +318,9 @@ static gboolean session_save()
     GList *it;
     gboolean success = TRUE;
 
+    if (save_file)
+        unlink(save_file)
+
     /* this algo is from metacity */
     filename = g_strdup_printf("%d-%d-%u.obs",
                                (gint) time(NULL),