diff --git a/share/examples/bhyve/vmrun.sh b/share/examples/bhyve/vmrun.sh
--- a/share/examples/bhyve/vmrun.sh
+++ b/share/examples/bhyve/vmrun.sh
@@ -62,7 +62,7 @@
 	echo "                [-L <VNC IP for UEFI framebuffer>]"
 	echo "                [-m <memsize>]" \
 	    "[-n <network adapter emulation type>]"
-	echo "                [-p <bus/slot/func>]"
+	echo "                [-p <pcidev>]"
 	echo "                [-P <port>] [-t <tapdev>] <vmname>"
 	echo ""
 	echo "       -h: display this help message"
@@ -87,8 +87,7 @@
 	echo "       -m: memory size (default: ${DEFAULT_MEMSIZE})"
 	echo "       -n: network adapter emulation type" \
 	    "(default: ${DEFAULT_NIC})"
-	echo "       -p: pass-through a host PCI device at bus/slot/func" \
-	    "(e.g. 10/0/0)"
+	echo "       -p: pass-through a host PCI device (e.g ehci0)"
 	echo "       -P: UEFI GOP VNC port (default: ${DEFAULT_VNCPORT})"
 	echo "       -t: tap device for virtio-net (default: $DEFAULT_TAPDEV)"
 	echo "       -T: Enable tablet device (for UEFI GOP)"
@@ -352,7 +351,12 @@
 	i=0
 	while [ $i -lt $pass_total ] ; do
 	    eval "pass=\$pass_dev${i}"
-	    devargs="$devargs -s $nextslot:0,passthru,${pass} "
+	    passno="$(
+		pciconf -l | grep "${pass}@" | awk '{print $1}' | cut -f2 -d@ |
+		cut -f2- -d: | sed 's/:$//' | tr : /
+	    )"
+	    test -z "${passno}" && errmsg "${pass} is not a host PCI device"
+	    devargs="$devargs -s $nextslot:0,passthru,${passno} "
 	    nextslot=$(($nextslot + 1))
 	    i=$(($i + 1))
         done