diff --git a/hw/xfree86/drivers/modesetting/driver.c b/hw/xfree86/drivers/modesetting/driver.c
index f371198a9..21e75c762 100644
--- a/hw/xfree86/drivers/modesetting/driver.c
+++ b/hw/xfree86/drivers/modesetting/driver.c
@@ -851,13 +851,11 @@ ms_get_drm_master_fd(ScrnInfoPtr pScrn)
 
         PciInfo = xf86GetPciInfoForEntity(ms->pEnt->index);
         if (PciInfo) {
-            BusID = XNFalloc(64);
-            sprintf(BusID, "PCI:%d:%d:%d",
-                    ((PciInfo->domain << 8) | PciInfo->bus),
-                    PciInfo->dev, PciInfo->func);
+            if ((BusID = ms_DRICreatePCIBusID(PciInfo)) != NULL) {
+                ms->fd = drmOpen(NULL, BusID);
+                free(BusID);
+            }
         }
-        ms->fd = drmOpen(NULL, BusID);
-        free(BusID);
     }
     else
 #endif