diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index bcbd2266d3..2ab9801fab 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -119,7 +119,7 @@ char_u *get_function_name(expand_T *xp, int idx)
     intidx = -1;
   if (intidx < 0) {
     name = get_user_func_name(xp, idx);
-    if (name != NULL) {
+    if (name != NULL && *name != NUL) {
       if (*name != '<' && STRNCMP("g:", xp->xp_pattern, 2) == 0) {
         return cat_prefix_varname('g', name);
       }
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index 34126b49fa..9d5987ba30 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -602,6 +602,11 @@ func Test_cmdline_complete_user_func()
   " g: prefix also works
   call feedkeys(":echo g:Test_cmdline_complete_user_f\<Tab>\<Home>\"\<cr>", 'tx')
   call assert_match('"echo g:Test_cmdline_complete_user_func', @:)
+
+  " using g: prefix does not result in just "g:" matches from a lambda
+  let Fx = { a ->  a }
+  call feedkeys(":echo g:\<Tab>\<Home>\"\<cr>", 'tx')
+  call assert_match('"echo g:[A-Z]', @:)
 endfunc
 
 func Test_cmdline_complete_user_names()