diff --git a/hw/pci-host/bonito.c b/hw/pci-host/bonito.c
index 751fdcec68..a57e81e3a9 100644
--- a/hw/pci-host/bonito.c
+++ b/hw/pci-host/bonito.c
@@ -187,7 +187,7 @@ FIELD(BONGENCFG, PCIQUEUE,      12, 1)
 #define BONITO_PCICONF_FUN_MASK        0x700    /* [10:8] */
 #define BONITO_PCICONF_FUN_OFFSET      8
 #define BONITO_PCICONF_REG_MASK_DS     (~3)         /* Per datasheet */
-#define BONITO_PCICONF_REG_MASK        0xFC
+#define BONITO_PCICONF_REG_MASK_HW     0xff         /* As seen running PMON */
 #define BONITO_PCICONF_REG_OFFSET      0
 
 
@@ -466,7 +466,7 @@ static uint32_t bonito_sbridge_pciaddr(void *opaque, hwaddr addr)
              BONITO_PCICONF_IDSEL_OFFSET;
     devno = ctz32(idsel);
     funno = (cfgaddr & BONITO_PCICONF_FUN_MASK) >> BONITO_PCICONF_FUN_OFFSET;
-    regno = (cfgaddr & BONITO_PCICONF_REG_MASK) >> BONITO_PCICONF_REG_OFFSET;
+    regno = (cfgaddr & BONITO_PCICONF_REG_MASK_HW) >> BONITO_PCICONF_REG_OFFSET;
 
     if (idsel == 0) {
         error_report("error in bonito pci config address 0x" TARGET_FMT_plx