diff --git a/staticaddr/deposit/deposit.go b/staticaddr/deposit/deposit.go
index 2121d170..cb9723e1 100644
--- a/staticaddr/deposit/deposit.go
+++ b/staticaddr/deposit/deposit.go
@@ -73,6 +73,12 @@ func (d *Deposit) IsInFinalState() bool {
 	d.Lock()
 	defer d.Unlock()
 
+	return d.isInFinalStateNoLock()
+}
+
+// isInFinalStateNoLock returns true if the deposit is final without acquiring
+// the deposit lock.
+func (d *Deposit) isInFinalStateNoLock() bool {
 	return d.state == Expired || d.state == Withdrawn ||
 		d.state == LoopedIn || d.state == HtlcTimeoutSwept ||
 		d.state == ChannelPublished
diff --git a/staticaddr/deposit/manager.go b/staticaddr/deposit/manager.go
index b0a2427e..b4ea2779 100644
--- a/staticaddr/deposit/manager.go
+++ b/staticaddr/deposit/manager.go
@@ -520,6 +520,10 @@ func (m *Manager) TransitionDeposits(ctx context.Context, deposits []*Deposit,
 
 	outpoints := make([]wire.OutPoint, len(deposits))
 	for i, d := range deposits {
+		if d == nil {
+			return fmt.Errorf("nil deposit at index %d", i)
+		}
+
 		outpoints[i] = d.OutPoint
 	}
 	if err := CheckDuplicates(outpoints); err != nil {
@@ -536,6 +540,13 @@ func (m *Manager) TransitionDeposits(ctx context.Context, deposits []*Deposit,
 
 	lockDeposits(deposits)
 	defer unlockDeposits(deposits)
+	for _, deposit := range deposits {
+		if deposit.isInFinalStateNoLock() {
+			return fmt.Errorf("deposit %v is no longer active in "+
+				"state %v", deposit.OutPoint, deposit.state)
+		}
+	}
+
 	for _, sm := range stateMachines {
 		err := sm.SendEvent(ctx, event, nil)
 		if err != nil {