diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index a55de7e..a78cf19 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1370,6 +1370,9 @@
     dany[i] = i
   endfor
   assert_equal({a: 'a', 12: 12}, dany)
+
+  # result of glob() is "any", runtime type check
+  var sl: list<string> = glob('*.txt', false, true) + ['']
 enddef
 
 " test multiply, divide, modulo
diff --git a/src/version.c b/src/version.c
index 2dbf24a..65a3f50 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2584,
+/**/
     2583,
 /**/
     2582,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index c781060..7c1dca5 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -4450,7 +4450,7 @@
 }
 
 /*
- *      +	number addition
+ *      +	number addition or list/blobl concatenation
  *      -	number subtraction
  *      ..	string concatenation
  */
@@ -4532,6 +4532,7 @@
 	else
 	{
 	    generate_ppconst(cctx, ppconst);
+	    ppconst->pp_is_const = FALSE;
 	    if (*op == '.')
 	    {
 		if (may_generate_2STRING(-2, cctx) == FAIL