diff --git a/sys/riscv/riscv/timer.c b/sys/riscv/riscv/timer.c
--- a/sys/riscv/riscv/timer.c
+++ b/sys/riscv/riscv/timer.c
@@ -120,7 +120,8 @@
 riscv_timer_et_stop(struct eventtimer *et)
 {
 
-	/* TODO */
+	/* Disable timer interrupts. */
+	csr_clear(sie, SIE_STIE);
 
 	return (0);
 }