diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index bf49740..f82a11c 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -743,6 +743,7 @@
   call term_sendkeys(a:buf, ":diffupdate!\<CR>")
   " trailing : for leaving the cursor on the command line
   call term_sendkeys(a:buf, ":set diffopt=internal,filler" . a:extra . "\<CR>:")
+  call term_wait(a:buf)
   call VerifyScreenDump(a:buf, a:dumpfile, {})
 endfunc