diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index b93cc6d..d1160d0 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -242,43 +242,60 @@
   bwipe! b
 endfunc
 
+" :diffput and :diffget completes names of buffers which
+" are in diff mode and which are different then current buffer.
+" No completion when the current window is not in diff mode.
 func Test_diffget_diffput_completion()
-  new Xdiff1 | diffthis
-  new Xdiff2 | diffthis
-  new Xdiff3 | diffthis
-  new Xdiff4
+  e            Xdiff1 | diffthis
+  botright new Xdiff2
+  botright new Xdiff3 | split | diffthis
+  botright new Xdiff4 | diffthis
 
-  " :diffput and :diffget completes names of buffers which
-  " are in diff mode and which are different then current buffer.
-  b Xdiff1
+  wincmd t
+  call assert_equal('Xdiff1', bufname('%'))
   call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"diffput Xdiff2 Xdiff3', @:)
+  call assert_equal('"diffput Xdiff3 Xdiff4', @:)
   call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"diffget Xdiff2 Xdiff3', @:)
-  call assert_equal(['Xdiff2', 'Xdiff3'], getcompletion('', 'diff_buffer'))
+  call assert_equal('"diffget Xdiff3 Xdiff4', @:)
+  call assert_equal(['Xdiff3', 'Xdiff4'], getcompletion('', 'diff_buffer'))
 
-  b Xdiff2
-  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"diffput Xdiff1 Xdiff3', @:)
-  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"diffget Xdiff1 Xdiff3', @:)
-  call assert_equal(['Xdiff1', 'Xdiff3'], getcompletion('', 'diff_buffer'))
-
-  b Xdiff3
-  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"diffput Xdiff1 Xdiff2', @:)
-  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"diffget Xdiff1 Xdiff2', @:)
-  call assert_equal(['Xdiff1', 'Xdiff2'], getcompletion('', 'diff_buffer'))
-
-  " No completion when in Xdiff4, it's not in diff mode.
-  b Xdiff4
+  " Xdiff2 is not in diff mode, so no completion for :diffput, :diffget
+  wincmd j
+  call assert_equal('Xdiff2', bufname('%'))
   call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"diffput ', @:)
   call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"diffget ', @:)
   call assert_equal([], getcompletion('', 'diff_buffer'))
 
+  " Xdiff3 is split in 2 windows, only the top one is in diff mode.
+  " So completion of :diffput :diffget only happens in the top window.
+  wincmd j
+  call assert_equal('Xdiff3', bufname('%'))
+  call assert_equal(1, &diff)
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput Xdiff1 Xdiff4', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget Xdiff1 Xdiff4', @:)
+  call assert_equal(['Xdiff1', 'Xdiff4'], getcompletion('', 'diff_buffer'))
+
+  wincmd j
+  call assert_equal('Xdiff3', bufname('%'))
+  call assert_equal(0, &diff)
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput ', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget ', @:)
+  call assert_equal([], getcompletion('', 'diff_buffer'))
+
+  wincmd j
+  call assert_equal('Xdiff4', bufname('%'))
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput Xdiff1 Xdiff3', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget Xdiff1 Xdiff3', @:)
+  call assert_equal(['Xdiff1', 'Xdiff3'], getcompletion('', 'diff_buffer'))
+
   %bwipe
 endfunc