diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 8353c81..295f9b9 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -242,11 +242,31 @@ setup2:
 	movw	%ax, %es
 	cld
 
+# Apparently some ancient versions of LILO invoked the kernel
+# with %ss != %ds, which happened to work by accident for the
+# old code.  If the CAN_USE_HEAP flag is set in loadflags, or
+# %ss != %ds, then adjust the stack pointer.
+	testb	$CAN_USE_HEAP, loadflags
+	jnz 2f
+
+	# No CAN_USE_HEAP
+	movw	%ss, %dx
+	cmpw	%ax, %dx	# %ds == %ss?
+	je	3f		# If so, assume %sp is valid
+
+	# If not, use the default value from heap_end_ptr
+	# as the %sp value -- it's the best we can do with an
+	# impossible situation.
+2:
+	movw	%ax, %ss
+	movw	heap_end_ptr, %sp
+	
 # Stack paranoia: align the stack and make sure it is good
 # for both 16- and 32-bit references.  In particular, if we
 # were meant to have been using the full 16-bit segment, the
 # caller might have set %sp to zero, which breaks %esp-based
 # references.
+3:	
 	andw	$~3, %sp	# dword align (might as well...)
 	jnz	1f
 	movw	$0xfffc, %sp	# Make sure we're not zero