diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 458ac38..17bfd1b 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -756,7 +756,7 @@
     augroup END
 
     func WriteErrors()
-      call writefile([execute("messages")], "Xerrors")
+      call writefile([execute("messages")], "XerrorsBwipe")
     endfunc
     au VimLeave * call WriteErrors()
   [CODE]
@@ -764,11 +764,11 @@
   call writefile(content, 'Xvimrc', 'D')
   call system(GetVimCommand('Xvimrc') .. ' --not-a-term --noplugins -S Session.vim -c cq')
   sleep 100m
-  let errors = join(readfile('Xerrors'))
+  let errors = join(readfile('XerrorsBwipe'))
   call assert_match('E814:', errors)
 
   set swapfile
-  for file in ['Session.vim', 'Xerrors']
+  for file in ['Session.vim', 'XerrorsBwipe']
     call delete(file)
   endfor
 endfunc
@@ -781,16 +781,16 @@
       edit foo1
       au BufNew,BufAdd,BufWinEnter,BufEnter,BufLeave,BufWinLeave,BufUnload,VimEnter foo* ball
       edit foo2
-      call writefile(['OK'], 'Xerrors')
+      call writefile(['OK'], 'XerrorsBlast')
       qall
   [CODE]
 
   call writefile(content, 'XblastBall', 'D')
   call system(GetVimCommand() .. ' --clean -S XblastBall')
   sleep 100m
-  call assert_match('OK', readfile('Xerrors')->join())
+  call assert_match('OK', readfile('XerrorsBlast')->join())
 
-  call delete('Xerrors')
+  call delete('XerrorsBlast')
 endfunc
 
 " SEGV occurs in older versions.
@@ -817,7 +817,7 @@
     au SessionLoadPost * call DeleteInactiveBufs()
 
     func WriteErrors()
-      call writefile([execute("messages")], "Xerrors")
+      call writefile([execute("messages")], "XerrorsPost")
     endfunc
     au VimLeave * call WriteErrors()
   [CODE]
@@ -825,13 +825,13 @@
   call writefile(content, 'Xvimrc', 'D')
   call system(GetVimCommand('Xvimrc') .. ' --not-a-term --noplugins -S Session.vim -c cq')
   sleep 100m
-  let errors = join(readfile('Xerrors'))
+  let errors = join(readfile('XerrorsPost'))
   " This probably only ever matches on unix.
   call assert_notmatch('Caught deadly signal SEGV', errors)
   call assert_match('SessionLoadPost DONE', errors)
 
   set swapfile
-  for file in ['Session.vim', 'Xerrors']
+  for file in ['Session.vim', 'XerrorsPost']
     call delete(file)
   endfor
 endfunc
diff --git a/src/testdir/test_startup.vim b/src/testdir/test_startup.vim
index 573b676..6cc62ad 100644
--- a/src/testdir/test_startup.vim
+++ b/src/testdir/test_startup.vim
@@ -306,9 +306,9 @@
   call writefile(lines, 'Xbadfile.c')
 
   let after =<< trim [CODE]
-    call writefile([&errorfile, string(getpos("."))], "Xtestout")
+    call writefile([&errorfile, string(getpos("."))], "XtestoutQarg")
     copen
-    w >> Xtestout
+    w >> XtestoutQarg
     qall
   [CODE]
 
@@ -316,30 +316,30 @@
   call assert_equal('errors.err', &errorfile)
   call writefile(["Xbadfile.c:4:12: error: expected ';' before '}' token"], 'errors.err')
   if RunVim([], after, '-q')
-    let lines = readfile('Xtestout')
+    let lines = readfile('XtestoutQarg')
     call assert_equal(['errors.err',
 	\              '[0, 4, 12, 0]',
 	\              "Xbadfile.c|4 col 12| error: expected ';' before '}' token"],
 	\             lines)
   endif
-  call delete('Xtestout')
+  call delete('XtestoutQarg')
   call delete('errors.err')
 
-  " Test with explicit argument '-q Xerrors' (with space).
-  call writefile(["Xbadfile.c:4:12: error: expected ';' before '}' token"], 'Xerrors')
-  if RunVim([], after, '-q Xerrors')
-    let lines = readfile('Xtestout')
-    call assert_equal(['Xerrors',
+  " Test with explicit argument '-q XerrorsQarg' (with space).
+  call writefile(["Xbadfile.c:4:12: error: expected ';' before '}' token"], 'XerrorsQarg')
+  if RunVim([], after, '-q XerrorsQarg')
+    let lines = readfile('XtestoutQarg')
+    call assert_equal(['XerrorsQarg',
 	\              '[0, 4, 12, 0]',
 	\              "Xbadfile.c|4 col 12| error: expected ';' before '}' token"],
 	\             lines)
   endif
-  call delete('Xtestout')
+  call delete('XtestoutQarg')
 
-  " Test with explicit argument '-qXerrors' (without space).
-  if RunVim([], after, '-qXerrors')
-    let lines = readfile('Xtestout')
-    call assert_equal(['Xerrors',
+  " Test with explicit argument '-qXerrorsQarg' (without space).
+  if RunVim([], after, '-qXerrorsQarg')
+    let lines = readfile('XtestoutQarg')
+    call assert_equal(['XerrorsQarg',
 	\              '[0, 4, 12, 0]',
 	\              "Xbadfile.c|4 col 12| error: expected ';' before '}' token"],
 	\             lines)
@@ -350,8 +350,8 @@
   call assert_equal(3, v:shell_error)
 
   call delete('Xbadfile.c')
-  call delete('Xtestout')
-  call delete('Xerrors')
+  call delete('XtestoutQarg')
+  call delete('XerrorsQarg')
 endfunc
 
 " Test the -V[N]{filename} argument to set the 'verbose' option to N
diff --git a/src/version.c b/src/version.c
index dd12a26..4ba0b1e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    428,
+/**/
     427,
 /**/
     426,