diff --git a/storage/pebble/approvals.go b/storage/pebble/approvals.go
index a521e6757af..2f4b1575197 100644
--- a/storage/pebble/approvals.go
+++ b/storage/pebble/approvals.go
@@ -74,10 +74,6 @@ func (r *ResultApprovals) byChunk(resultID flow.Identifier, chunkIndex uint64) f
 
 func (r *ResultApprovals) index(resultID flow.Identifier, chunkIndex uint64, approvalID flow.Identifier) func(storage.PebbleReaderBatchWriter) error {
 	return func(tx storage.PebbleReaderBatchWriter) error {
-		// acquring the lock to prevent dirty reads of check conflicted approvals
-		r.indexing.Lock()
-		defer r.indexing.Unlock()
-
 		r, w := tx.ReaderWriter()
 
 		var storedApprovalID flow.Identifier
@@ -118,6 +114,14 @@ func (r *ResultApprovals) Store(approval *flow.ResultApproval) error {
 // just calling the method once; still the method succeeds on each call).
 // this method is concurrent-safe
 func (r *ResultApprovals) Index(resultID flow.Identifier, chunkIndex uint64, approvalID flow.Identifier) error {
+	// acquring the lock to prevent dirty reads when checking conflicted approvals
+	// how it works:
+	// the lock can only be acquired after the index operation is committed to the database,
+	// since the index operation is the only operation that would affect the reads operation,
+	// no writes can go through util the lock is released, so locking here could prevent dirty reads.
+	r.indexing.Lock()
+	defer r.indexing.Unlock()
+
 	err := operation.WithReaderBatchWriter(r.db, r.index(resultID, chunkIndex, approvalID))
 	if err != nil {
 		return fmt.Errorf("could not index result approval: %w", err)
diff --git a/storage/pebble/approvals_test.go b/storage/pebble/approvals_test.go
index 39f60c5bdaf..f1f6ed2ef45 100644
--- a/storage/pebble/approvals_test.go
+++ b/storage/pebble/approvals_test.go
@@ -1,12 +1,15 @@
 package pebble_test
 
 import (
+	"errors"
+	"sync"
 	"testing"
 
 	"github.com/cockroachdb/pebble"
 	"github.com/stretchr/testify/require"
 
 	"github.com/onflow/flow-go/module/metrics"
+	"github.com/onflow/flow-go/storage"
 	bstorage "github.com/onflow/flow-go/storage/pebble"
 	"github.com/onflow/flow-go/utils/unittest"
 )
@@ -72,9 +75,58 @@ func TestApprovalStoreTwoDifferentApprovalsShouldFail(t *testing.T) {
 		err = store.Store(approval2)
 		require.NoError(t, err)
 
-		// TODO: fix later once implement insert and upsert
-		// err = store.Index(approval1.Body.ExecutionResultID, approval1.Body.ChunkIndex, approval2.ID())
-		// require.Error(t, err)
-		// require.True(t, errors.Is(err, storage.ErrDataMismatch))
+		// index again with a different approval should fail
+		err = store.Index(approval1.Body.ExecutionResultID, approval1.Body.ChunkIndex, approval2.ID())
+		require.Error(t, err)
+		require.True(t, errors.Is(err, storage.ErrDataMismatch))
+	})
+}
+
+// verify that storing and indexing two conflicting approvals concurrently should fail
+// one of them is succeed, the other one should fail
+func TestApprovalStoreTwoDifferentApprovalsConcurrently(t *testing.T) {
+	unittest.RunWithPebbleDB(t, func(db *pebble.DB) {
+		metrics := metrics.NewNoopCollector()
+		store := bstorage.NewResultApprovals(metrics, db)
+
+		approval1 := unittest.ResultApprovalFixture()
+		approval2 := unittest.ResultApprovalFixture()
+
+		var wg sync.WaitGroup
+		wg.Add(2)
+
+		var firstIndexErr, secondIndexErr error
+
+		// First goroutine stores and indexes the first approval.
+		go func() {
+			defer wg.Done()
+
+			err := store.Store(approval1)
+			require.NoError(t, err)
+
+			firstIndexErr = store.Index(approval1.Body.ExecutionResultID, approval1.Body.ChunkIndex, approval1.ID())
+		}()
+
+		// Second goroutine stores and tries to index the second approval for the same chunk.
+		go func() {
+			defer wg.Done()
+
+			err := store.Store(approval2)
+			require.NoError(t, err)
+
+			secondIndexErr = store.Index(approval1.Body.ExecutionResultID, approval1.Body.ChunkIndex, approval2.ID())
+		}()
+
+		// Wait for both goroutines to finish
+		wg.Wait()
+
+		// Check that one of the Index operations succeeded and the other failed
+		if firstIndexErr == nil {
+			require.Error(t, secondIndexErr)
+			require.True(t, errors.Is(secondIndexErr, storage.ErrDataMismatch))
+		} else {
+			require.NoError(t, secondIndexErr)
+			require.True(t, errors.Is(firstIndexErr, storage.ErrDataMismatch))
+		}
 	})
 }