diff --git a/sys/dev/si/si_pci.c b/sys/dev/si/si_pci.c
index 7aa390fca3fa..81c74e1fa2e9 100644
--- a/sys/dev/si/si_pci.c
+++ b/sys/dev/si/si_pci.c
@@ -105,6 +105,29 @@ si_pci_attach(device_t dev)
 		goto fail;
 	}
 
+	if (pci_get_devid(dev) == 0x200011cb) {
+		int rid;
+		struct resource *plx_res;
+		uint32_t *addr;
+		uint32_t oldvalue;
+
+		/* Perform a PLX control register fixup */
+		rid = PCIR_BAR(0);
+		plx_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
+		    RF_ACTIVE);
+		if (plx_res == NULL) {
+			device_printf(dev, "couldn't map plx registers\n");
+		} else {
+			addr = rman_get_virtual(plx_res);
+			oldvalue = addr[0x50 / 4];
+			if (oldvalue != 0x18260000) {
+				device_printf(dev, "PLX register 0x50: 0x%08x changed to 0x%08x\n", oldvalue, 0x18260000);
+				addr[0x50 / 4] = 0x18260000;
+			}
+			bus_release_resource(dev, SYS_RES_MEMORY, rid, plx_res);
+		}
+	}
+
 	error = siattach(dev);
 	if (error)
 		goto fail;