diff --git a/src/rtkit.c b/src/rtkit.c
index 226680475..7e22b0a71 100644
--- a/src/rtkit.c
+++ b/src/rtkit.c
@@ -438,7 +438,7 @@ int rtkit_recv(rtkit_dev_t *rtk, struct rtkit_message *msg)
                 }
                 break;
             case RTKIT_EP_OSLOG:
-                rtkit_printf("unknown oslog message %x\n", msg->msg);
+                rtkit_printf("unknown oslog message %lx\n", msg->msg);
                 break;
             default:
                 rtkit_printf("message to unknown system endpoint 0x%02x: %lx\n", msg->ep, msg->msg);