diff --git a/sndiod/siofile.c b/sndiod/siofile.c
index e1f3542..8cb2827 100644
--- a/sndiod/siofile.c
+++ b/sndiod/siofile.c
@@ -376,18 +376,18 @@ siofile_run(void *arg)
 			if (!siofile_rec(f))
 				return;
 #ifdef DEBUG
-			if (f->rused < d->round) {
+			f->rused -= d->round;
+			if (f->rused >= d->round) {
 				siofile_log(f);
-				log_puts(": missed clock tick, rused = ");
+				log_puts(": rec hw xrun, rused = ");
 				log_puti(f->rused);
 				log_puts("/");
 				log_puti(d->bufsz);
 				log_puts("\n");
 				panic();
 			}
-			f->rused -= d->round;
-			if (f->rused < 0) {
-				/* rec buffer size is not known */
+			if (f->rused < 0 || f->rused >= d->bufsz) {
+				/* device driver or libsndio bug */
 				siofile_log(f);
 				log_puts(": out of bounds rused = ");
 				log_puti(f->rused);
@@ -415,7 +415,7 @@ siofile_run(void *arg)
 				return;
 #ifdef DEBUG
 			f->pused += d->round;
-			if (d->prime == 0 && f->pused < d->bufsz - d->round) {
+			if (d->prime == 0 && f->pused <= d->bufsz - d->round) {
 				siofile_log(f);
 				log_puts(": play hw xrun, pused = ");
 				log_puti(f->pused);
@@ -424,7 +424,7 @@ siofile_run(void *arg)
 				log_puts("\n");
 			}
 			if (f->pused < 0 || f->pused > d->bufsz) {
-				/* this is a device drivers or libsndio bug */
+				/* device driver or libsndio bug */
 				siofile_log(f);
 				log_puts(": out of bounds pused = ");
 				log_puti(f->pused);