diff --git a/src/nvim/usercmd.c b/src/nvim/usercmd.c
index 6bff66dca2..3eb67a21f0 100644
--- a/src/nvim/usercmd.c
+++ b/src/nvim/usercmd.c
@@ -415,7 +415,7 @@ char *get_user_cmd_complete(expand_T *xp, int idx)
     return NULL;
   }
   char *cmd_compl = get_command_complete(idx);
-  if (cmd_compl == NULL) {
+  if (cmd_compl == NULL || idx == EXPAND_USER_LUA) {
     return "";
   }
   return cmd_compl;
diff --git a/test/functional/editor/completion_spec.lua b/test/functional/editor/completion_spec.lua
index 3f19596bd7..d543de4acd 100644
--- a/test/functional/editor/completion_spec.lua
+++ b/test/functional/editor/completion_spec.lua
@@ -4,7 +4,7 @@ local Screen = require('test.functional.ui.screen')
 
 local assert_alive = n.assert_alive
 local clear, feed = n.clear, n.feed
-local eval, eq, neq = n.eval, t.eq, t.neq
+local eval, eq, neq, ok = n.eval, t.eq, t.neq, t.ok
 local feed_command, source, expect = n.feed_command, n.source, n.expect
 local fn = n.fn
 local command = n.command
@@ -947,6 +947,12 @@ describe('completion', function()
     eq('SpecialKey', fn.getcompletion('set winhighlight=NonText:', 'cmdline')[1])
   end)
 
+  it('cmdline completion for -complete does not contain spaces', function()
+    for _, str in ipairs(fn.getcompletion('command -complete=', 'cmdline')) do
+      ok(not str:find(' '), 'string without spaces', str)
+    end
+  end)
+
   describe('from the commandline window', function()
     it('is cleared after CTRL-C', function()
       feed('q:')