diff --git a/patches/patchinstall.sh b/patches/patchinstall.sh
index 4cc6660b..a96e70e9 100755
--- a/patches/patchinstall.sh
+++ b/patches/patchinstall.sh
@@ -6281,6 +6281,7 @@ if test "$enable_widl_SLTG_Typelib_Support" -eq 1; then
 	patch_apply widl-SLTG_Typelib_Support/0018-widl-Fix-generation-of-resources-containing-an-old-t.patch
 	patch_apply widl-SLTG_Typelib_Support/0019-widl-Add-oldtlb-switch-in-usage-message.patch
 	patch_apply widl-SLTG_Typelib_Support/0020-stdole32.tlb-Compile-typelib-with-oldtlb.patch
+	patch_apply widl-SLTG_Typelib_Support/0021-widl-Avoid-relying-on-side-effects-when-marking-func.patch
 	(
 		echo '+    { "Dmitry Timoshkov", "widl: Add initial implementation of SLTG typelib generator.", 1 },';
 		echo '+    { "Dmitry Timoshkov", "widl: Add support for structures.", 1 },';
@@ -6302,6 +6303,7 @@ if test "$enable_widl_SLTG_Typelib_Support" -eq 1; then
 		echo '+    { "Dmitry Timoshkov", "widl: Fix generation of resources containing an old typelib.", 1 },';
 		echo '+    { "Sebastian Lackner", "widl: Add --oldtlb switch in usage message.", 1 },';
 		echo '+    { "Sebastian Lackner", "stdole32.tlb: Compile typelib with --oldtlb.", 1 },';
+		echo '+    { "Dmitry Timoshkov", "widl: Avoid relying on side effects when marking function index as the last one.", 1 },';
 	) >> "$patchlist"
 fi
 
diff --git a/patches/widl-SLTG_Typelib_Support/0021-widl-Avoid-relying-on-side-effects-when-marking-func.patch b/patches/widl-SLTG_Typelib_Support/0021-widl-Avoid-relying-on-side-effects-when-marking-func.patch
new file mode 100644
index 00000000..6c07fc2c
--- /dev/null
+++ b/patches/widl-SLTG_Typelib_Support/0021-widl-Avoid-relying-on-side-effects-when-marking-func.patch
@@ -0,0 +1,33 @@
+From 2404f4a367d658dc2b54f89381e6038a1bb68660 Mon Sep 17 00:00:00 2001
+From: Dmitry Timoshkov <dmitry@baikal.ru>
+Date: Fri, 22 Jan 2016 11:52:22 +0800
+Subject: widl: Avoid relying on side effects when marking function index as
+ the last one.
+
+---
+ tools/widl/write_sltg.c | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/tools/widl/write_sltg.c b/tools/widl/write_sltg.c
+index bf2ba5f..acfc039 100644
+--- a/tools/widl/write_sltg.c
++++ b/tools/widl/write_sltg.c
+@@ -1465,11 +1465,12 @@ static void add_interface_typeinfo(struct sltg_typelib *typelib, type_t *iface)
+ 
+     STATEMENTS_FOR_EACH_FUNC(stmt_func, type_iface_get_stmts(iface))
+     {
+-        if (i == func_count - 1) i |= 0x80000000;
++        int idx = inherited_func_count + i;
++
++        if (i == func_count - 1) idx |= 0x80000000;
+ 
+         base_offset += add_func_desc(typelib, &data, stmt_func->u.var,
+-                                     inherited_func_count + i,
+-                                     dispid++, base_offset, &hrefmap);
++                                     idx, dispid + i, base_offset, &hrefmap);
+         i++;
+     }
+ 
+-- 
+2.6.4
+