Index: lib/rtl/image.c
===================================================================
--- lib/rtl/image.c	(revision 62704)
+++ lib/rtl/image.c	(working copy)
@@ -195,7 +195,7 @@
 
         /* It shouldn't be past 4GB either */
         if (DosHeader->e_lfanew >=
-            (MAXULONG - sizeof(IMAGE_DOS_SIGNATURE) - sizeof(IMAGE_FILE_HEADER)))
+            (MAXULONG - RTL_SIZEOF_THROUGH_FIELD(IMAGE_NT_HEADERS, FileHeader)))
         {
             /* Fail */
             DPRINT1("e_lfanew is larger than 4GB\n");
@@ -204,7 +204,7 @@
 
         /* And the whole file shouldn't overflow past 4GB */
         if ((DosHeader->e_lfanew +
-            sizeof(IMAGE_DOS_SIGNATURE) - sizeof(IMAGE_FILE_HEADER)) >= Size)
+            RTL_SIZEOF_THROUGH_FIELD(IMAGE_NT_HEADERS, FileHeader)) >= Size)
         {
             /* Fail */
             DPRINT1("PE is larger than 4GB\n");