diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 73251c0..8f11217 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -123,6 +123,10 @@
   var res2: bool = append(3, 'two')
   assert_equal(false, res2)
   assert_equal(['0', 'one', '1', 'two', '2'], getline(1, 6))
+
+  append(0, 'zero')
+  assert_equal('zero', getline(1))
+  bwipe!
 enddef
 
 def Test_balloon_show()
diff --git a/src/typval.c b/src/typval.c
index 8030c69..ca561dd 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -1621,7 +1621,7 @@
 
     if (argvars[0].v_type != VAR_STRING || !in_vim9script())
 	lnum = (linenr_T)tv_get_number_chk(&argvars[0], NULL);
-    if (lnum <= 0)  // no valid number, try using arg like line()
+    if (lnum < 0)  // no valid number, try using arg like line()
     {
 	int	fnum;
 	pos_T	*fp = var2fpos(&argvars[0], TRUE, &fnum, FALSE);
diff --git a/src/version.c b/src/version.c
index 00d2fd7..1f389e9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2670,
+/**/
     2669,
 /**/
     2668,