diff --git a/hw/pcnet.c b/hw/pcnet.c
index db52dc59e1..6dfdcc420f 100644
--- a/hw/pcnet.c
+++ b/hw/pcnet.c
@@ -1562,8 +1562,24 @@ void pcnet_h_reset(void *opaque)
 
     /* Initialize the PROM */
 
+    /*
+      Datasheet: http://pdfdata.datasheetsite.com/web/24528/AM79C970A.pdf
+      page 95
+    */
     memcpy(s->prom, s->conf.macaddr.a, 6);
+    /* Reserved Location: must be 00h */
+    s->prom[6] = s->prom[7] = 0x00;
+    /* Reserved Location: must be 00h */
+    s->prom[8] = 0x00;
+    /* Hardware ID: must be 11h if compatibility to AMD drivers is desired */
+    s->prom[9] = 0x11;
+    /* User programmable space, init with 0 */
+    s->prom[10] = s->prom[11] = 0x00;
+    /* LSByte of two-byte checksum, which is the sum of bytes 00h-0Bh
+       and bytes 0Eh and 0Fh, must therefore be initialized with 0! */
     s->prom[12] = s->prom[13] = 0x00;
+    /* Must be ASCII W (57h) if compatibility to AMD
+       driver software is desired */
     s->prom[14] = s->prom[15] = 0x57;
 
     for (i = 0,checksum = 0; i < 16; i++)