diff --git a/src/evalfunc.c b/src/evalfunc.c
index 1abcd5e..0d17b9e 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -340,7 +340,7 @@
 }
 
 /*
- * Check "type" is the same type as the previous argument
+ * Check "type" is the same type as the previous argument.
  * Must not be used for the first argcheck_T entry.
  */
     static int
@@ -352,6 +352,21 @@
 }
 
 /*
+ * Check "type" is the same basic type as the previous argument, checks list or
+ * dict vs other type, but not member type.
+ * Must not be used for the first argcheck_T entry.
+ */
+    static int
+arg_same_struct_as_prev(type_T *type, argcontext_T *context)
+{
+    type_T *prev_type = context->arg_types[context->arg_idx - 1];
+
+    if (prev_type->tt_type != context->arg_types[context->arg_idx]->tt_type)
+	return check_arg_type(prev_type, type, context->arg_idx + 1);
+    return OK;
+}
+
+/*
  * Check "type" is an item of the list or blob of the previous arg.
  * Must not be used for the first argcheck_T entry.
  */
@@ -394,6 +409,7 @@
 argcheck_T arg1_float_or_nr[] = {arg_float_or_nr};
 argcheck_T arg2_listblob_item[] = {arg_list_or_blob, arg_item_of_prev};
 argcheck_T arg23_extend[] = {arg_list_or_dict, arg_same_as_prev, arg_extend3};
+argcheck_T arg23_extendnew[] = {arg_list_or_dict, arg_same_struct_as_prev, arg_extend3};
 argcheck_T arg3_insert[] = {arg_list_or_blob, arg_item_of_prev, arg_number};
 
 /*
@@ -877,6 +893,8 @@
 			ret_string,	    f_expandcmd},
     {"extend",		2, 3, FEARG_1,	    arg23_extend,
 			ret_first_arg,	    f_extend},
+    {"extendnew",	2, 3, FEARG_1,	    arg23_extendnew,
+			ret_first_cont,	    f_extendnew},
     {"feedkeys",	1, 2, FEARG_1,	    NULL,
 			ret_void,	    f_feedkeys},
     {"file_readable",	1, 1, FEARG_1,	    NULL,	// obsolete
diff --git a/src/list.c b/src/list.c
index 2b44eba..f7842fa 100644
--- a/src/list.c
+++ b/src/list.c
@@ -2454,14 +2454,11 @@
 }
 
 /*
- * "extend(list, list [, idx])" function
- * "extend(dict, dict [, action])" function
+ * "extend()" or "extendnew()" function.  "is_new" is TRUE for extendnew().
  */
-    void
-f_extend(typval_T *argvars, typval_T *rettv)
+    static void
+extend(typval_T *argvars, typval_T *rettv, char_u *arg_errmsg, int is_new)
 {
-    char_u      *arg_errmsg = (char_u *)N_("extend() argument");
-
     if (argvars[0].v_type == VAR_LIST && argvars[1].v_type == VAR_LIST)
     {
 	list_T		*l1, *l2;
@@ -2476,8 +2473,16 @@
 	    return;
 	}
 	l2 = argvars[1].vval.v_list;
-	if (!value_check_lock(l1->lv_lock, arg_errmsg, TRUE) && l2 != NULL)
+	if ((is_new || !value_check_lock(l1->lv_lock, arg_errmsg, TRUE))
+								 && l2 != NULL)
 	{
+	    if (is_new)
+	    {
+		l1 = list_copy(l1, FALSE, get_copyID());
+		if (l1 == NULL)
+		    return;
+	    }
+
 	    if (argvars[2].v_type != VAR_UNKNOWN)
 	    {
 		before = (long)tv_get_number_chk(&argvars[2], &error);
@@ -2500,7 +2505,14 @@
 		item = NULL;
 	    list_extend(l1, l2, item);
 
-	    copy_tv(&argvars[0], rettv);
+	    if (is_new)
+	    {
+		rettv->v_type = VAR_LIST;
+		rettv->vval.v_list = l1;
+		rettv->v_lock = FALSE;
+	    }
+	    else
+		copy_tv(&argvars[0], rettv);
 	}
     }
     else if (argvars[0].v_type == VAR_DICT && argvars[1].v_type == VAR_DICT)
@@ -2516,8 +2528,16 @@
 	    return;
 	}
 	d2 = argvars[1].vval.v_dict;
-	if (!value_check_lock(d1->dv_lock, arg_errmsg, TRUE) && d2 != NULL)
+	if ((is_new || !value_check_lock(d1->dv_lock, arg_errmsg, TRUE))
+								 && d2 != NULL)
 	{
+	    if (is_new)
+	    {
+		d1 = dict_copy(d1, FALSE, get_copyID());
+		if (d1 == NULL)
+		    return;
+	    }
+
 	    // Check the third argument.
 	    if (argvars[2].v_type != VAR_UNKNOWN)
 	    {
@@ -2540,11 +2560,42 @@
 
 	    dict_extend(d1, d2, action);
 
-	    copy_tv(&argvars[0], rettv);
+	    if (is_new)
+	    {
+		rettv->v_type = VAR_DICT;
+		rettv->vval.v_dict = d1;
+		rettv->v_lock = FALSE;
+	    }
+	    else
+		copy_tv(&argvars[0], rettv);
 	}
     }
     else
-	semsg(_(e_listdictarg), "extend()");
+	semsg(_(e_listdictarg), is_new ? "extendnew()" : "extend()");
+}
+
+/*
+ * "extend(list, list [, idx])" function
+ * "extend(dict, dict [, action])" function
+ */
+    void
+f_extend(typval_T *argvars, typval_T *rettv)
+{
+    char_u      *errmsg = (char_u *)N_("extend() argument");
+
+    extend(argvars, rettv, errmsg, FALSE);
+}
+
+/*
+ * "extendnew(list, list [, idx])" function
+ * "extendnew(dict, dict [, action])" function
+ */
+    void
+f_extendnew(typval_T *argvars, typval_T *rettv)
+{
+    char_u      *errmsg = (char_u *)N_("extendnew() argument");
+
+    extend(argvars, rettv, errmsg, TRUE);
 }
 
 /*
diff --git a/src/proto/list.pro b/src/proto/list.pro
index 2699050..b77add5 100644
--- a/src/proto/list.pro
+++ b/src/proto/list.pro
@@ -52,6 +52,7 @@
 void f_add(typval_T *argvars, typval_T *rettv);
 void f_count(typval_T *argvars, typval_T *rettv);
 void f_extend(typval_T *argvars, typval_T *rettv);
+void f_extendnew(typval_T *argvars, typval_T *rettv);
 void f_insert(typval_T *argvars, typval_T *rettv);
 void f_remove(typval_T *argvars, typval_T *rettv);
 void f_reverse(typval_T *argvars, typval_T *rettv);
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index 762a517..051a37c 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -864,6 +864,18 @@
   call assert_fails("call extend(g:, {'-!' : 10})", 'E461:')
 endfunc
 
+func Test_listdict_extendnew()
+  " Test extendnew() with lists
+  let l = [1, 2, 3]
+  call assert_equal([1, 2, 3, 4, 5], extendnew(l, [4, 5]))
+  call assert_equal([1, 2, 3], l)
+
+  " Test extend() with dictionaries.
+  let d = {'a': {'b': 'B'}}
+  call assert_equal({'a': {'b': 'B'}, 'c': 'cc'}, extendnew(d, {'c': 'cc'}))
+  call assert_equal({'a': {'b': 'B'}}, d)
+endfunc
+
 func s:check_scope_dict(x, fixed)
   func s:gen_cmd(cmd, x)
     return substitute(a:cmd, '\<x\ze:', a:x, 'g')
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 673f0c0..c867266 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -243,6 +243,16 @@
   CheckDefFailure(['extend({a: 1}, {b: 2}, 1)'], 'E1013: Argument 3: type mismatch, expected string but got number')
 enddef
 
+def Test_extendnew()
+  assert_equal([1, 2, 'a'], extendnew([1, 2], ['a']))
+  assert_equal({one: 1, two: 'a'}, extendnew({one: 1}, {two: 'a'}))
+
+  CheckDefFailure(['extendnew({a: 1}, 42)'], 'E1013: Argument 2: type mismatch, expected dict<number> but got number')
+  CheckDefFailure(['extendnew({a: 1}, [42])'], 'E1013: Argument 2: type mismatch, expected dict<number> but got list<number>')
+  CheckDefFailure(['extendnew([1, 2], "x")'], 'E1013: Argument 2: type mismatch, expected list<number> but got string')
+  CheckDefFailure(['extendnew([1, 2], {x: 1})'], 'E1013: Argument 2: type mismatch, expected list<number> but got dict<number>')
+enddef
+
 def Test_extend_return_type()
   var l = extend([1, 2], [3])
   var res = 0
diff --git a/src/version.c b/src/version.c
index 1832108..d4b5dde 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2336,
+/**/
     2335,
 /**/
     2334,