diff --git a/src/errors.h b/src/errors.h
index 31f275d..8d8a2ca 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -850,3 +850,5 @@
 	INIT(= N_("E1252: String, List or Blob required for argument %d"));
 EXTERN char e_string_expected_for_argument_nr[]
 	INIT(= N_("E1253: String expected for argument %d"));
+EXTERN char e_cannot_use_script_variable_in_for_loop[]
+	INIT(= N_("E1254: Cannot use script variable in for loop"));
diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index 2d86b6b..6347a28 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -1392,6 +1392,10 @@
   s:theList[1] = 44
   assert_equal([1, 44, 3], s:theList)
 
+  if 0
+    lockvar whatever
+  endif
+
   var d = {a: 1, b: 2}
   d.a = 3
   d.b = 4
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index af80935..fe985de 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -2963,7 +2963,7 @@
 
 def Test_for_loop_script_var()
   # cannot use s:var in a :def function
-  CheckDefFailure(['for s:var in range(3)', 'echo 3'], 'E461:')
+  CheckDefFailure(['for s:var in range(3)', 'echo 3'], 'E1254:')
 
   # can use s:var in Vim9 script, with or without s:
   var lines =<< trim END
diff --git a/src/version.c b/src/version.c
index a7f372d..38c9e00 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3859,
+/**/
     3858,
 /**/
     3857,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 2b27f51..4bce997 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -8333,7 +8333,6 @@
 		lhs_type = parse_type(&p, cctx->ctx_type_list, TRUE);
 	    }
 
-	    // Script var is not supported.
 	    if (get_var_dest(name, &dest, CMD_for, &opt_flags,
 					      &vimvaridx, &type, cctx) == FAIL)
 		goto failed;
@@ -8351,6 +8350,13 @@
 	    }
 	    else
 	    {
+		// Script var is not supported.
+		if (STRNCMP(name, "s:", 2) == 0)
+		{
+		    emsg(_(e_cannot_use_script_variable_in_for_loop));
+		    goto failed;
+		}
+
 		if (!valid_varname(arg, (int)varlen, FALSE))
 		    goto failed;
 		if (lookup_local(arg, varlen, NULL, cctx) == OK)
@@ -8359,12 +8365,6 @@
 		    goto failed;
 		}
 
-		if (STRNCMP(name, "s:", 2) == 0)
-		{
-		    semsg(_(e_cannot_declare_script_variable_in_function), name);
-		    goto failed;
-		}
-
 		// Reserve a variable to store "var".
 		where.wt_index = var_list ? idx + 1 : 0;
 		where.wt_variable = TRUE;