1 files changed, 4 insertions, 4 deletions
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index e336bdb..6e2ad82 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -814,12 +814,12 @@ static uint32_t find_free_port_id(VirtIOSerial *vser)
 
     max_nr_ports = vser->serial.max_virtserial_ports;
     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
-        uint32_t map, bit;
+        uint32_t map, zeroes;
 
         map = vser->ports_map[i];
-        bit = ffs(~map);
-        if (bit) {
-            return (bit - 1) + i * 32;
+        zeroes = ctz32(~map);
+        if (zeroes != 32) {
+            return zeroes + i * 32;
         }
     }
     return VIRTIO_CONSOLE_BAD_ID;