diff --git a/internal/test/ledger/ledger.go b/internal/test/ledger/ledger.go
index 6e4e3ead..8c9f7430 100644
--- a/internal/test/ledger/ledger.go
+++ b/internal/test/ledger/ledger.go
@@ -64,13 +64,13 @@ func (ls MockLedgerState) StakeRegistration(
 }
 
 func (ls MockLedgerState) PoolCurrentState(
-	poolKeyHash []byte,
+	poolKeyHash common.PoolKeyHash,
 ) (*common.PoolRegistrationCertificate, *uint64, error) {
 	for _, cert := range ls.MockPoolRegistration {
 		if string(
 			common.Blake2b224(cert.Operator).Bytes(),
 		) == string(
-			poolKeyHash,
+			common.Blake2b224(poolKeyHash).Bytes(),
 		) {
 			// pretend latest registration is current; no retirement support in mock
 			c := cert
diff --git a/ledger/alonzo/rules.go b/ledger/alonzo/rules.go
index 5419f3d1..37ee6162 100644
--- a/ledger/alonzo/rules.go
+++ b/ledger/alonzo/rules.go
@@ -289,7 +289,7 @@ func UtxoValidateValueNotConservedUtxo(
 	for _, cert := range tx.Certificates() {
 		switch tmpCert := cert.(type) {
 		case *common.PoolRegistrationCertificate:
-			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator).Bytes())
+			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator))
 			if err != nil {
 				return err
 			}
diff --git a/ledger/babbage/rules.go b/ledger/babbage/rules.go
index 2aa6e7ac..5071a484 100644
--- a/ledger/babbage/rules.go
+++ b/ledger/babbage/rules.go
@@ -275,7 +275,7 @@ func UtxoValidateValueNotConservedUtxo(
 	for _, cert := range tx.Certificates() {
 		switch tmpCert := cert.(type) {
 		case *common.PoolRegistrationCertificate:
-			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator).Bytes())
+			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator))
 			if err != nil {
 				return err
 			}
diff --git a/ledger/common/state.go b/ledger/common/state.go
index ec562d6b..eb96cd47 100644
--- a/ledger/common/state.go
+++ b/ledger/common/state.go
@@ -35,7 +35,7 @@ type PoolState interface {
 	// PoolCurrentState returns the latest active registration certificate for the given pool key hash.
 	// It also returns the epoch of a pending retirement certificate, if one exists.
 	// If the pool is not registered, the registration certificate will be nil.
-	PoolCurrentState([]byte) (*PoolRegistrationCertificate, *uint64, error)
+	PoolCurrentState(PoolKeyHash) (*PoolRegistrationCertificate, *uint64, error)
 }
 
 // LedgerState defines the interface for querying the ledger
diff --git a/ledger/conway/rules.go b/ledger/conway/rules.go
index cfce8a33..37870808 100644
--- a/ledger/conway/rules.go
+++ b/ledger/conway/rules.go
@@ -272,7 +272,7 @@ func UtxoValidateValueNotConservedUtxo(
 	for _, cert := range tx.Certificates() {
 		switch tmpCert := cert.(type) {
 		case *common.PoolRegistrationCertificate:
-			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator).Bytes())
+			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator))
 			if err != nil {
 				return err
 			}
diff --git a/ledger/mary/rules.go b/ledger/mary/rules.go
index d7796aed..3d6520fd 100644
--- a/ledger/mary/rules.go
+++ b/ledger/mary/rules.go
@@ -175,7 +175,7 @@ func UtxoValidateValueNotConservedUtxo(
 	for _, cert := range tx.Certificates() {
 		switch tmpCert := cert.(type) {
 		case *common.PoolRegistrationCertificate:
-			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator).Bytes())
+			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator))
 			if err != nil {
 				return err
 			}
diff --git a/ledger/shelley/rules.go b/ledger/shelley/rules.go
index e0263d37..62ad73f6 100644
--- a/ledger/shelley/rules.go
+++ b/ledger/shelley/rules.go
@@ -196,7 +196,7 @@ func UtxoValidateValueNotConservedUtxo(
 	for _, cert := range tx.Certificates() {
 		switch tmpCert := cert.(type) {
 		case *common.PoolRegistrationCertificate:
-			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator).Bytes())
+			reg, _, err := ls.PoolCurrentState(common.Blake2b224(tmpCert.Operator))
 			if err != nil {
 				return err
 			}