diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 05e65e1..41ec7c7 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -1277,6 +1277,13 @@
     g:FLIST[0] = 22
     assert_equal([22], g:FLIST)
 
+    def SetGlobalConst()
+      const g:globConst = 123
+    enddef
+    SetGlobalConst()
+    assert_equal(123, g:globConst)
+    assert_true(islocked('g:globConst'))
+
     const w:FOO: number = 46
     assert_equal(46, w:FOO)
     const w:FOOS = 'wfoos'
@@ -1341,6 +1348,17 @@
 
   lines =<< trim END
     vim9script
+    def SetGlobalConst()
+      const g:globConst = 123
+    enddef
+    SetGlobalConst()
+    g:globConst = 234
+  END
+  CheckScriptFailure(lines, 'E741: Value is locked: globConst')
+  unlet g:globConst
+
+  lines =<< trim END
+    vim9script
     const cdict: dict<string> = {}
     def Change()
       cdict.foo = 'foo'
diff --git a/src/version.c b/src/version.c
index 68949e0..0fb8bc3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2687,
+/**/
     2686,
 /**/
     2685,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index fa73de2..ca1c89c 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -5752,7 +5752,8 @@
 				      &lhs->lhs_opt_flags, &lhs->lhs_vimvaridx,
 						 &lhs->lhs_type, cctx) == FAIL)
 	    return FAIL;
-	if (lhs->lhs_dest != dest_local)
+	if (lhs->lhs_dest != dest_local
+				 && cmdidx != CMD_const && cmdidx != CMD_final)
 	{
 	    // Specific kind of variable recognized.
 	    declare_error = is_decl;
@@ -6519,6 +6520,7 @@
 	else
 	{
 	    if (is_decl && cmdidx == CMD_const && (lhs.lhs_dest == dest_script
+						|| lhs.lhs_dest == dest_global
 						|| lhs.lhs_dest == dest_local))
 		// ":const var": lock the value, but not referenced variables
 		generate_LOCKCONST(cctx);
diff --git a/src/vim9execute.c b/src/vim9execute.c
index f15b93d..9b7f87b 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -963,9 +963,12 @@
 store_var(char_u *name, typval_T *tv)
 {
     funccal_entry_T entry;
+    int		    flags = ASSIGN_DECL;
 
+    if (tv->v_lock)
+	flags |= ASSIGN_CONST;
     save_funccal(&entry);
-    set_var_const(name, NULL, tv, FALSE, ASSIGN_DECL, 0);
+    set_var_const(name, NULL, tv, FALSE, flags, 0);
     restore_funccal();
 }