diff --git a/src/arch/i386/prefix/pxeprefix.S b/src/arch/i386/prefix/pxeprefix.S
index b541e4b..11dd45d 100644
--- a/src/arch/i386/prefix/pxeprefix.S
+++ b/src/arch/i386/prefix/pxeprefix.S
@@ -47,7 +47,7 @@ FILE_LICENCE ( GPL2_OR_LATER )
 	/* Set up stack just below 0x7c00 */
 	xorw	%ax, %ax
 	movw	%ax, %ss
-	movl	$0x7c00, %esp
+	movl	$0x7a00, %esp
 	/* Clear direction flag, for the sake of sanity */
 	cld
 	/* Print welcome message */
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S
index cb474e8..93f3f17 100644
--- a/src/arch/i386/prefix/romprefix.S
+++ b/src/arch/i386/prefix/romprefix.S
@@ -587,7 +587,7 @@ exec:	/* Set %ds = %cs */
 	/* Obtain a reasonably-sized temporary stack */
 	xorw	%ax, %ax
 	movw	%ax, %ss
-	movw	$0x7c00, %sp
+	movw	$0x7a00, %sp
 
 	/* Install gPXE */
 	movl	image_source, %esi