diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index 48ab69c..fff9ebd 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -1320,7 +1320,7 @@
   1,$delete
   call job_start('cat test_channel.vim', {'out_io': 'buffer', 'out_name': 'testout'})
   call WaitFor('line("$") > g:linecount')
-  call assert_true(line('$') > g:linecount)
+  call assert_inrange(g:linecount + 1, g:linecount + 2, line('$'))
   bwipe!
 endfunc