diff --git a/lib/srfi/1/test.sld b/lib/srfi/1/test.sld
index b280b12b..94910f88 100644
--- a/lib/srfi/1/test.sld
+++ b/lib/srfi/1/test.sld
@@ -77,6 +77,10 @@
       (test 'a (append '() 'a))
       (test '(x y) (append '(x y)))
       (test '() (append))
+      (test (list 'a) (append! '() (list 'a)))
+      (test (list 'a 'b) (append! (list 'a) '() '() (list 'b)))
+      (test (list 'x 'y) (append! (list 'x 'y)))
+      (test '() (append!))
       (test '(c b a) (reverse '(a b c)))
       (test '((e (f)) d (b c) a) (reverse '(a (b c) d (e (f)))))
       (test '((one 1 odd) (two 2 even) (three 3 odd)) (zip '(one two three) '(1 2 3) '(odd even odd even odd even odd even)))