diff --git a/build/jam/BuildSetup b/build/jam/BuildSetup
index 5942fccc81..07442bd796 100644
--- a/build/jam/BuildSetup
+++ b/build/jam/BuildSetup
@@ -171,6 +171,7 @@ switch $(HAIKU_CPU) {
 	{
 		HAIKU_DEFINES += __POWERPC__ ;
 		HAIKU_BOOT_PLATFORM = openfirmware ;
+		HAIKU_BOOT_FLOPPY_IMAGE_SIZE = 1440 ; # in kB
 		# offset in floppy image (>= sizeof(haiku_loader))
 		HAIKU_BOOT_ARCHIVE_IMAGE_OFFSET = 192 ; # in kB - unused yet
 	}
@@ -178,6 +179,7 @@ switch $(HAIKU_CPU) {
 	{
 		HAIKU_DEFINES += __INTEL__ ;
 		HAIKU_BOOT_PLATFORM = bios_ia32 ;
+		HAIKU_BOOT_FLOPPY_IMAGE_SIZE = 2880 ; # in kB
 		# offset in floppy image (>= sizeof(haiku_loader))
 		HAIKU_BOOT_ARCHIVE_IMAGE_OFFSET = 300 ; # in kB
 
@@ -190,6 +192,7 @@ switch $(HAIKU_CPU) {
 	{
 		HAIKU_DEFINES += __M68K__ ;
 		HAIKU_BOOT_PLATFORM = atari_m68k ;
+		HAIKU_BOOT_FLOPPY_IMAGE_SIZE = 1440 ; # in kB
 		# offset in floppy image (>= sizeof(haiku_loader))
 		HAIKU_BOOT_ARCHIVE_IMAGE_OFFSET = 130 ; # in kB
 	}
diff --git a/build/jam/ImageRules b/build/jam/ImageRules
index 679d65905f..1513ef4b1d 100644
--- a/build/jam/ImageRules
+++ b/build/jam/ImageRules
@@ -1056,6 +1056,7 @@ rule BuildFloppyBootImage image : haikuLoader : archive
 	Depends $(image) : $(haikuLoader) ;
 	Depends $(image) : $(archive) ;
 	#MakeLocateDebug $(image) ;
+	FLOPPY_IMAGE_SIZE on $(image) = $(HAIKU_BOOT_FLOPPY_IMAGE_SIZE) ;
 	ARCHIVE_IMAGE_OFFSET on $(image) = $(HAIKU_BOOT_ARCHIVE_IMAGE_OFFSET) ;
 	BuildFloppyBootImage1 $(image) : $(haikuLoader) $(archive) ;
 }
@@ -1064,7 +1065,7 @@ actions BuildFloppyBootImage1
 {
 	$(RM) $(<)
 	# make an empty image
-	dd if=/dev/zero of=$(<) bs=2k count=1440
+	dd if=/dev/zero of=$(<) bs=1k count=$(FLOPPY_IMAGE_SIZE)
 	# add haiku_loader
 	dd if=$(>[1]) of=$(<) conv=notrunc
 	# add the boot drivers tgz archive