diff --git a/internal/test/ledger/ledger.go b/internal/test/ledger/ledger.go
index 7382cc21..c9f14ce2 100644
--- a/internal/test/ledger/ledger.go
+++ b/internal/test/ledger/ledger.go
@@ -16,6 +16,7 @@ package test_ledger
 
 import (
 	"errors"
+	"time"
 
 	"github.com/blinklabs-io/gouroboros/ledger/common"
 )
@@ -77,3 +78,13 @@ func (ls MockLedgerState) PoolRegistration(
 	}
 	return ret, nil
 }
+
+func (ls MockLedgerState) SlotToTime(slot uint64) (time.Time, error) {
+	// TODO
+	return time.Now(), nil
+}
+
+func (ls MockLedgerState) TimeToSlot(t time.Time) (uint64, error) {
+	// TODO
+	return 0, nil
+}
diff --git a/ledger/common/state.go b/ledger/common/state.go
index d5a9aafd..8c9410f0 100644
--- a/ledger/common/state.go
+++ b/ledger/common/state.go
@@ -35,6 +35,7 @@ type CertState interface {
 type LedgerState interface {
 	UtxoState
 	CertState
+	SlotState
 	NetworkId() uint
 }