diff --git a/autoload/vimspector.vim b/autoload/vimspector.vim
index 7e71695..c3ead44 100644
--- a/autoload/vimspector.vim
+++ b/autoload/vimspector.vim
@@ -116,7 +116,8 @@ function! vimspector#ListBreakpoints() abort
 endfunction
 
 function! vimspector#CompleteOutput( ArgLead, CmdLine, CursorPos ) abort
-  return py3eval( '_vimspector_session.GetOutputBuffers()' )
+  let buffers = py3eval( '_vimspector_session.GetOutputBuffers()' )
+  return join( buffers, "\n" )
 endfunction
 
 function! vimspector#CompleteExpr( ArgLead, CmdLine, CursorPos ) abort
diff --git a/plugin/vimspector.vim b/plugin/vimspector.vim
index 10eb374..6034d53 100644
--- a/plugin/vimspector.vim
+++ b/plugin/vimspector.vim
@@ -74,7 +74,7 @@ endif
 command! -bar -nargs=1 -complete=customlist,vimspector#CompleteExpr
       \ VimspectorWatch
       \ call vimspector#AddWatch( <f-args> )
-command! -bar -nargs=1 -complete=customlist,vimspector#CompleteOutput
+command! -bar -nargs=1 -complete=custom,vimspector#CompleteOutput
       \ VimspectorShowOutput
       \ call vimspector#ShowOutput( <f-args> )
 command! -bar -nargs=1 -complete=customlist,vimspector#CompleteExpr