structure alignment issues?

[akcom]

Translating the following from windows:

--- C Code:

#define IMAGE_SIZEOF_SHORT_NAME              8

typedef struct _IMAGE_SECTION_HEADER {
     BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
     union {
             DWORD   PhysicalAddress;
             DWORD   VirtualSize;
     } Misc;
     DWORD   VirtualAddress;
     DWORD   SizeOfRawData;
     DWORD   PointerToRawData;
     DWORD   PointerToRelocations;
     DWORD   PointerToLinenumbers;
     WORD    NumberOfRelocations;
     WORD    NumberOfLinenumbers;
     DWORD   Characteristics;
} IMAGE_SECTION_HEADER, *PIMAGE_SECTION_HEADER;

#define IMAGE_SIZEOF_SECTION_HEADER          40

--- D Code:

const uint IMAGE_SIZEOF_SHORT_NAME = 8;
const uint IMAGE_SIZEOF_SECTION_HEADER = 40;

align struct ImageSectionHeader
{
     BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
     union Misc
	{
             DWORD   PhysicalAddress;
             DWORD   VirtualSize;
     }
     DWORD   VirtualAddress;
     DWORD   SizeOfRawData;
     DWORD   PointerToRawData;
     DWORD   PointerToRelocations;
     DWORD   PointerToLinenumbers;
     WORD    NumberOfRelocations;
     WORD    NumberOfLinenumbers;
     DWORD   Characteristics;
}
alias ImageSectionHeader IMAGE_SECTION_HEADER;
alias ImageSectionHeader *PIMAGE_SECTION_HEADER;

the problem is that ImageSectionHeader.sizeof == 36
Any ideas as to why?