diff --git a/header/header.go b/header/header.go
index 4db80d0ac3..fe7df77616 100644
--- a/header/header.go
+++ b/header/header.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"sync"
 	"time"
 
 	tmjson "github.com/tendermint/tendermint/libs/json"
@@ -38,6 +39,9 @@ type ExtendedHeader struct {
 	Commit       *core.Commit               `json:"commit"`
 	ValidatorSet *core.ValidatorSet         `json:"validator_set"`
 	DAH          *da.DataAvailabilityHeader `json:"dah"`
+
+	hashOnce sync.Once
+	hash     []byte
 }
 
 // MakeExtendedHeader assembles new ExtendedHeader.
@@ -90,11 +94,13 @@ func (eh *ExtendedHeader) Time() time.Time {
 	return eh.RawHeader.Time
 }
 
-// Hash returns Hash of the wrapped RawHeader.
-// NOTE: It purposely overrides Hash method of RawHeader to get it directly from Commit without
-// recomputing.
+// Hash returns Hash of the wrapped [RawHeader].
+// Value is cached to not be recomuted every call.
 func (eh *ExtendedHeader) Hash() libhead.Hash {
-	return eh.Commit.BlockID.Hash.Bytes()
+	eh.hashOnce.Do(func() {
+		eh.hash = eh.RawHeader.Hash()
+	})
+	return eh.hash
 }
 
 // LastHeader returns the Hash of the last wrapped RawHeader.
@@ -147,7 +153,7 @@ func (eh *ExtendedHeader) Validate() error {
 	if eh.Commit.Height != eh.RawHeader.Height {
 		return fmt.Errorf("header and commit height mismatch: %d vs %d", eh.RawHeader.Height, eh.Commit.Height)
 	}
-	if hhash, chash := eh.RawHeader.Hash(), eh.Commit.BlockID.Hash; !bytes.Equal(hhash, chash) {
+	if hhash, chash := eh.Hash(), eh.Commit.BlockID.Hash; !bytes.Equal(hhash, chash) {
 		return fmt.Errorf("commit signs block %X, header is block %X", chash, hhash)
 	}
 
@@ -223,7 +229,12 @@ func (eh *ExtendedHeader) UnmarshalBinary(data []byte) error {
 		return err
 	}
 
-	*eh = *out
+	*eh = ExtendedHeader{
+		RawHeader:    out.RawHeader,
+		Commit:       out.Commit,
+		ValidatorSet: out.ValidatorSet,
+		DAH:          out.DAH,
+	}
 	return nil
 }
 
diff --git a/header/headertest/verify_test.go b/header/headertest/verify_test.go
index c55d810593..f1140f3601 100644
--- a/header/headertest/verify_test.go
+++ b/header/headertest/verify_test.go
@@ -30,7 +30,12 @@ func TestVerify(t *testing.T) {
 		},
 		{
 			prepare: func() *header.ExtendedHeader {
-				untrusted := *untrustedAdj
+				untrusted := header.ExtendedHeader{
+					RawHeader:    untrustedAdj.RawHeader,
+					Commit:       untrustedAdj.Commit,
+					ValidatorSet: untrustedAdj.ValidatorSet,
+					DAH:          untrustedAdj.DAH,
+				}
 				untrusted.ValidatorsHash = tmrand.Bytes(32)
 				return &untrusted
 			},
@@ -38,7 +43,12 @@ func TestVerify(t *testing.T) {
 		},
 		{
 			prepare: func() *header.ExtendedHeader {
-				untrusted := *untrustedAdj
+				untrusted := header.ExtendedHeader{
+					RawHeader:    untrustedAdj.RawHeader,
+					Commit:       untrustedAdj.Commit,
+					ValidatorSet: untrustedAdj.ValidatorSet,
+					DAH:          untrustedAdj.DAH,
+				}
 				untrusted.RawHeader.LastBlockID.Hash = tmrand.Bytes(32)
 				return &untrusted
 			},
@@ -46,7 +56,12 @@ func TestVerify(t *testing.T) {
 		},
 		{
 			prepare: func() *header.ExtendedHeader {
-				untrusted := *untrustedNonAdj
+				untrusted := header.ExtendedHeader{
+					RawHeader:    untrustedNonAdj.RawHeader,
+					Commit:       untrustedNonAdj.Commit,
+					ValidatorSet: untrustedNonAdj.ValidatorSet,
+					DAH:          untrustedNonAdj.DAH,
+				}
 				untrusted.Commit = NewTestSuite(t, 2, 0).Commit(RandRawHeader(t))
 				return &untrusted
 			},