diff --git a/devices/common/scsi/sc53c94.cpp b/devices/common/scsi/sc53c94.cpp
index 613a954..ab25b60 100644
--- a/devices/common/scsi/sc53c94.cpp
+++ b/devices/common/scsi/sc53c94.cpp
@@ -280,9 +280,14 @@ void Sc53C94::exec_command()
         // assert RST line
         this->bus_obj->assert_ctrl_line(this->my_bus_id, SCSI_CTRL_RST);
         // release RST line after 25 us
+        if (my_timer_id) {
+            TimerManager::get_instance()->cancel_timer(this->my_timer_id);
+            my_timer_id = 0;
+        }
         my_timer_id = TimerManager::get_instance()->add_oneshot_timer(
             USECS_TO_NSECS(25),
             [this]() {
+                my_timer_id = 0;
                 this->bus_obj->release_ctrl_line(this->my_bus_id, SCSI_CTRL_RST);
         });
         if (!(config1 & 0x40)) {
@@ -406,10 +411,16 @@ uint8_t Sc53C94::fifo_pop()
 
 void Sc53C94::seq_defer_state(uint64_t delay_ns)
 {
+    if (seq_timer_id) {
+        TimerManager::get_instance()->cancel_timer(this->seq_timer_id);
+        seq_timer_id = 0;
+    }
+
     seq_timer_id = TimerManager::get_instance()->add_oneshot_timer(
         delay_ns,
         [this]() {
             // re-enter the sequencer with the state specified in next_state
+            this->seq_timer_id = 0;
             this->cur_state = this->next_state;
             this->sequencer();
     });
@@ -576,6 +587,7 @@ void Sc53C94::notify(ScsiMsg msg_type, int param)
         if (this->target_id == param) {
             // cancel selection timeout timer
             TimerManager::get_instance()->cancel_timer(this->seq_timer_id);
+            seq_timer_id = 0;
             this->cur_state = SeqState::SEL_END;
             this->sequencer();
         } else {