diff --git a/src/pciinit.c b/src/pciinit.c
index 1d0f784..29b3901 100644
--- a/src/pciinit.c
+++ b/src/pciinit.c
@@ -139,11 +139,13 @@ static void pci_bios_init_device(u16 bdf)
             int ofs;
             u32 val, size;
 
-            if (i == PCI_ROM_SLOT)
+            if (i == PCI_ROM_SLOT) {
                 ofs = PCI_ROM_ADDRESS;
-            else
+                pci_config_writel(bdf, ofs, PCI_ROM_ADDRESS_MASK);
+            } else {
                 ofs = PCI_BASE_ADDRESS_0 + i * 4;
-            pci_config_writel(bdf, ofs, 0xffffffff);
+                pci_config_writel(bdf, ofs, PCI_BASE_ADDRESS_IO_MASK);
+            }
             val = pci_config_readl(bdf, ofs);
             if (val != 0) {
                 size = (~(val & ~0xf)) + 1;