diff --git a/src/testdir/test_backup.vim b/src/testdir/test_backup.vim
index 0981efd..ce2bfe7 100644
--- a/src/testdir/test_backup.vim
+++ b/src/testdir/test_backup.vim
@@ -1,7 +1,7 @@
 " Tests for the backup function
 
 func Test_backup()
-  set backup backupdir=.
+  set backup backupdir=. backupskip=
   new
   call setline(1, ['line1', 'line2'])
   :f Xbackup.txt
@@ -12,13 +12,13 @@
   let l = readfile('Xbackup.txt~')
   call assert_equal(['line1', 'line2'], l)
   bw!
-  set backup&vim backupdir&vim
+  set backup&vim backupdir&vim backupskip&vim
   call delete('Xbackup.txt')
   call delete('Xbackup.txt~')
 endfunc
 
 func Test_backup2()
-  set backup backupdir=.//
+  set backup backupdir=.// backupskip=
   new
   call setline(1, ['line1', 'line2', 'line3'])
   :f Xbackup.txt
@@ -34,11 +34,11 @@
   bw!
   call delete('Xbackup.txt')
   call delete(f)
-  set backup&vim backupdir&vim
+  set backup&vim backupdir&vim backupskip&vim
 endfunc
 
 func Test_backup2_backupcopy()
-  set backup backupdir=.// backupcopy=yes
+  set backup backupdir=.// backupcopy=yes backupskip=
   new
   call setline(1, ['line1', 'line2', 'line3'])
   :f Xbackup.txt
@@ -54,5 +54,5 @@
   bw!
   call delete('Xbackup.txt')
   call delete(f)
-  set backup&vim backupdir&vim backupcopy&vim
+  set backup&vim backupdir&vim backupcopy&vim backupskip&vim
 endfunc