diff --git a/src/arch/x86/drivers/net/undinet.c b/src/arch/x86/drivers/net/undinet.c
index 43cb18bfe..cdb39c74f 100644
--- a/src/arch/x86/drivers/net/undinet.c
+++ b/src/arch/x86/drivers/net/undinet.c
@@ -972,6 +972,10 @@ int undinet_probe ( struct undi_device *undi, struct device *dev ) {
 	}
 	DBGC ( undinic, "UNDINIC %p has MAC address %s and IRQ %d\n",
 	       undinic, eth_ntoa ( netdev->hw_addr ), undinic->irq );
+	if ( undinic->irq ) {
+		/* Sanity check - prefix should have disabled the IRQ */
+		assert ( ! irq_enabled ( undinic->irq ) );
+	}
 
 	/* Get interface information */
 	memset ( &undi_iface, 0, sizeof ( undi_iface ) );
diff --git a/src/arch/x86/prefix/pxeprefix.S b/src/arch/x86/prefix/pxeprefix.S
index 0842fcac4..2ac1bc76d 100644
--- a/src/arch/x86/prefix/pxeprefix.S
+++ b/src/arch/x86/prefix/pxeprefix.S
@@ -1,6 +1,7 @@
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
 
 #define PXENV_UNDI_SHUTDOWN		0x0005
+#define PXENV_UNDI_GET_INFORMATION	0x000c
 #define	PXENV_UNDI_GET_NIC_TYPE		0x0012
 #define PXENV_UNDI_GET_IFACE_INFO	0x0013
 #define	PXENV_STOP_UNDI			0x0015
@@ -380,6 +381,33 @@ no_physical_device:
 
 99:
 
+/*****************************************************************************
+ * Get IRQ number
+ *****************************************************************************
+ */
+get_irq:
+	/* Issue PXENV_UNDI_GET_INFORMATION */
+	movw	$PXENV_UNDI_GET_INFORMATION, %bx
+	call	pxe_call
+	jnc	1f
+	call	print_pxe_error
+	jmp	99f
+1:	/* Check for a valid IRQ number */
+	movw	( pxe_parameter_structure + 0x04 ), %ax
+	testw	%ax, %ax
+	jz	99f
+	cmpw	$15, %ax
+	ja	99f
+	/* Store IRQ number */
+	movw	%ax, undi_irq
+	movw	$10f, %si
+	call	print_message
+	call	print_word
+	.section ".prefix.data", "aw", @progbits
+10:	.asciz	", IRQ "
+	.previous
+99:
+
 /*****************************************************************************
  * Determine interface type
  *****************************************************************************
@@ -470,6 +498,30 @@ pxe_cmdline:
 	.long	0
 	.previous
 
+/*****************************************************************************
+ * Ensure NIC interrupt is disabled
+ *****************************************************************************
+ */
+disable_irq:
+	/* Check for a recorded IRQ number */
+	movw	undi_irq, %cx
+	testw	%cx, %cx
+	jz	99f
+	/* Calculate IMR */
+	movw	%cx, %dx
+	shlw	$4, %dx
+	andb	$0x80, %dl
+	orb	$0x21, %dl
+	/* Calculate mask value */
+	movb	$0x01, %bl
+	andb	$0x07, %cl
+	shlb	%cl, %bl
+	/* Mask interrupt */
+	inb	%dx, %al
+	orb	%bl, %al
+	outb	%al, %dx
+99:
+
 /*****************************************************************************
  * Leave NIC in a safe state
  *****************************************************************************
@@ -759,6 +811,8 @@ undi_data_segoff:
 undi_data_size:		.word 0
 undi_data_segment:	.word 0
 
+undi_irq:		.word 0
+
 pxe_hacks:		.word 0
 
 /* The following fields are part of a struct undi_device */