Index: dll/win32/msi/dialog.c
===================================================================
--- dll/win32/msi/dialog.c	(revision 73519)
+++ dll/win32/msi/dialog.c	(working copy)
@@ -3165,13 +3165,13 @@
                 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;