diff --git a/src/testdir/test_swap.vim b/src/testdir/test_swap.vim
index 90afb4d..caacd7e 100644
--- a/src/testdir/test_swap.vim
+++ b/src/testdir/test_swap.vim
@@ -201,8 +201,8 @@
   " This test won't work as root because root can successfully run kill(1, 0)
   if !IsRoot()
     " Write the swapfile with a modified PID, now it will be automatically
-    " deleted. Process one should never be Vim.
-    let swapfile_bytes[24:27] = 0z01000000
+    " deleted. Process 0x3fffffff most likely does not exist.
+    let swapfile_bytes[24:27] = 0zffffff3f
     call writefile(swapfile_bytes, swapfile_name)
     let s:swapname = ''
     split XswapfileText