diff --git a/src/window.c b/src/window.c
index 43c9ed2..06f97de 100644
--- a/src/window.c
+++ b/src/window.c
@@ -6563,7 +6563,7 @@
 		&& check_snapshot_rec(sn->fr_next, fr->fr_next) == FAIL)
 	    || (sn->fr_child != NULL
 		&& check_snapshot_rec(sn->fr_child, fr->fr_child) == FAIL)
-	    || !win_valid(sn->fr_win))
+	    || (sn->fr_win != NULL && !win_valid(sn->fr_win)))
 	return FAIL;
     return OK;
 }