diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 844f589..f9533fa 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -4504,6 +4504,7 @@
   CheckScreendump
 
   let lines =<< trim [SCRIPT]
+    call test_override('alloc_lines', 1)
     set wildmenu wildcharm=<f5>
     call setline(1, ['the', 'these', 'the', 'foobar', 'thethe', 'thethere'])
   [SCRIPT]