diff --git a/sdk/tools/winesync/msi_staging/0001-msi__Do_not_sign_extend_after_multiplying.diff b/sdk/tools/winesync/msi_staging/0001-msi__Do_not_sign_extend_after_multiplying.diff
new file mode 100644
index 00000000000..307428366a3
--- /dev/null
+++ b/sdk/tools/winesync/msi_staging/0001-msi__Do_not_sign_extend_after_multiplying.diff
@@ -0,0 +1,20 @@
+diff --git a/dll/win32/msi/dialog.c b/dll/win32/msi/dialog.c
+index 9d82be8..8e4c151 100644
+--- a/dll/win32/msi/dialog.c
++++ b/dll/win32/msi/dialog.c
+@@ -3186,13 +3186,13 @@ static LONGLONG msi_vcl_get_cost( msi_dialog *dialog )
+                 MSICOSTTREE_SELFONLY, INSTALLSTATE_LOCAL, &each_cost)))
+         {
+             /* each_cost is in 512-byte units */
+-            total_cost += each_cost * 512;
++            total_cost += ((LONGLONG)each_cost) * 512;
+         }
+         if (ERROR_SUCCESS == (MSI_GetFeatureCost(dialog->package, feature,
+                 MSICOSTTREE_SELFONLY, INSTALLSTATE_ABSENT, &each_cost)))
+         {
+             /* each_cost is in 512-byte units */
+-            total_cost -= each_cost * 512;
++            total_cost -= ((LONGLONG)each_cost) * 512;
+         }
+     }
+     return total_cost;