diff --git a/src/system/boot/loader/Jamfile b/src/system/boot/loader/Jamfile
index 7aa6a1f7ca..a576f2c5ae 100644
--- a/src/system/boot/loader/Jamfile
+++ b/src/system/boot/loader/Jamfile
@@ -54,17 +54,23 @@ for platform in [ MultiBootSubDirSetup ] {
 				{
 					DEFINES +=
 						ALTERNATE_BOOT_ARCH=\\\"x86_64\\\"
-						BOOT_SUPPORT_ELF64
-
 						BOOT_SUPPORT_PARTITION_EFI
 
 						#BOOT_SUPPORT_FILE_SYSTEM_FAT
 					;
+
 					if $(TARGET_BOOT_PLATFORM) != efi {
 						DEFINES +=
 							_BOOT_PLATFORM_BIOS
 							BOOT_SUPPORT_ELF32
+							BOOT_SUPPORT_ELF64
 						;
+					} else {
+						if $(TARGET_ARCH) = x86_64 {
+							DEFINES += BOOT_SUPPORT_ELF64 ;
+						} else {
+							DEFINES += BOOT_SUPPORT_ELF32 ;
+						}
 					}
 				}
 				case "sparc" :