Index: sys/riscv/riscv/timer.c
===================================================================
--- sys/riscv/riscv/timer.c
+++ sys/riscv/riscv/timer.c
@@ -143,7 +143,10 @@
 
 	sc = (struct riscv_timer_softc *)arg;
 
-	csr_clear(sip, SIP_STIP);
+	if (has_sstc)
+		csr_write(stimecmp, -1UL);
+	else
+		csr_clear(sip, SIP_STIP);
 
 	if (sc->et.et_active)
 		sc->et.et_event_cb(&sc->et, sc->et.et_arg);