diff --git a/src/testdir/test_window_cmd.vim b/src/testdir/test_window_cmd.vim
index 91adb9b..c8afab3 100644
--- a/src/testdir/test_window_cmd.vim
+++ b/src/testdir/test_window_cmd.vim
@@ -557,7 +557,7 @@
   1wincmd w
   split
   4wincmd w
-  resize + 5
+  resize +5
   " left column has three windows, equalized heights.
   " right column has two windows, top one a bit higher
   let height_1 = winheight(1)