diff --git a/src/arch/i386/prefix/nbiprefix.S b/src/arch/i386/prefix/nbiprefix.S
index 20d224d69..06e7df5b7 100644
--- a/src/arch/i386/prefix/nbiprefix.S
+++ b/src/arch/i386/prefix/nbiprefix.S
@@ -54,6 +54,10 @@ _nbi_start:
 	/* Install iPXE */
 	call	install
 
+	/* Set up real-mode stack */
+	movw	%bx, %ss
+	movw	$_estack16, %sp
+
 	/* Jump to .text16 segment */
 	pushw	%ax
 	pushw	$1f