diff --git a/src/arch/i386/interface/pxe/pxe_call.c b/src/arch/i386/interface/pxe/pxe_call.c
index 3a5f4c75..3ccb7fb5 100644
--- a/src/arch/i386/interface/pxe/pxe_call.c
+++ b/src/arch/i386/interface/pxe/pxe_call.c
@@ -347,6 +347,9 @@ __cdecl void pxe_loader_call ( struct i386_all_regs *ix86 ) {
 	/* Copy parameter block from caller */
 	copy_from_user ( &params, uparams, 0, sizeof ( params ) );
 
+	/* Fill in ROM segment address */
+	ppxe.UNDIROMID.segment = ix86->segs.ds;
+
 	/* Set default status in case child routine fails to do so */
 	params.Status = PXENV_STATUS_FAILURE;
 
diff --git a/src/arch/i386/interface/pxe/pxe_entry.S b/src/arch/i386/interface/pxe/pxe_entry.S
index 204894ef..c55e581f 100644
--- a/src/arch/i386/interface/pxe/pxe_entry.S
+++ b/src/arch/i386/interface/pxe/pxe_entry.S
@@ -35,7 +35,7 @@ ppxe:
 	.byte 0				/* StructCksum */
 	.byte 0				/* StructRev */
 	.byte 0				/* reserved_1 */
-	.word 0, 0			/* UNDIROMID */
+	.word undiheader, 0		/* UNDIROMID */
 	.word 0, 0			/* BaseROMID */
 	.word pxe_entry_sp, 0		/* EntryPointSP */
 	.word pxe_entry_esp, 0		/* EntryPointESP */
@@ -55,6 +55,11 @@ pxe_segments:
 	.equ	pxe_length, . - ppxe
 	.size	ppxe, . - ppxe
 
+	/* Define undiheader=0 as a weak symbol for non-ROM builds */
+	.section ".weak"
+	.weak	undiheader
+undiheader:
+
 /****************************************************************************
  * PXENV+ structure
  ****************************************************************************
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S
index 90ddd106..f9b9e169 100644
--- a/src/arch/i386/prefix/romprefix.S
+++ b/src/arch/i386/prefix/romprefix.S
@@ -112,7 +112,8 @@ prodstr_separator:
 prodstr_pci_id:
 	.asciz	"xx:xx.x)"		/* Filled in by init code */
 	.size prodstr, . - prodstr
-	
+
+	.globl	undiheader	
 undiheader:
 	.ascii	"UNDI"			/* Signature */
 	.byte	undiheader_len		/* Length of structure */
@@ -524,18 +525,22 @@ undiloader:
 	/* Save registers */
 	pushl	%esi
 	pushl	%edi
+	pushw	%ds
 	pushw	%es
 	pushw	%bx
+	/* ROM segment address to %ds */
+	pushw	%cs
+	popw	%ds
 	/* UNDI loader parameter structure address into %es:%di */
 	movw	%sp, %bx
-	movw	%ss:16(%bx), %di
-	movw	%ss:18(%bx), %es
+	movw	%ss:18(%bx), %di
+	movw	%ss:20(%bx), %es
 	/* Install to specified real-mode addresses */
 	pushw	%di
 	movw	%es:12(%di), %bx
 	movw	%es:14(%di), %ax
-	movl	%cs:image_source, %esi
-	movl	%cs:decompress_to, %edi
+	movl	image_source, %esi
+	movl	decompress_to, %edi
 	call	install_prealloc
 	popw	%di
 	/* Call UNDI loader C code */
@@ -550,6 +555,7 @@ undiloader:
 	/* Restore registers and return */
 	popw	%bx
 	popw	%es
+	popw	%ds
 	popl	%edi
 	popl	%esi
 	lret
diff --git a/src/arch/i386/scripts/i386.lds b/src/arch/i386/scripts/i386.lds
index a5a01056..7d63dae6 100644
--- a/src/arch/i386/scripts/i386.lds
+++ b/src/arch/i386/scripts/i386.lds
@@ -30,6 +30,16 @@ SECTIONS {
      *
      */
 
+    /*
+     * Weak symbols that need zero values if not otherwise defined
+     */
+
+    . = 0;
+    .weak : AT ( 0 ) {
+	*(.weak)
+    }
+    _assert = ASSERT ( ( . == 0 ), ".weak is non-zero length" );
+
     /*
      * The prefix
      */