diff --git a/lite/memprovider.go b/lite/memprovider.go
index 9c454be02..ed7cd7725 100644
--- a/lite/memprovider.go
+++ b/lite/memprovider.go
@@ -3,11 +3,13 @@ package lite
 import (
 	"encoding/hex"
 	"sort"
+	"sync"
 
 	liteErr "github.com/tendermint/tendermint/lite/errors"
 )
 
 type memStoreProvider struct {
+	mtx sync.RWMutex
 	// byHeight is always sorted by Height... need to support range search (nil, h]
 	// btree would be more efficient for larger sets
 	byHeight fullCommits
@@ -45,6 +47,9 @@ func (m *memStoreProvider) StoreCommit(fc FullCommit) error {
 
 	// store the valid fc
 	key := m.encodeHash(fc.ValidatorsHash())
+
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
 	m.byHash[key] = fc
 	m.byHeight = append(m.byHeight, fc)
 	sort.Sort(m.byHeight)
@@ -53,6 +58,9 @@ func (m *memStoreProvider) StoreCommit(fc FullCommit) error {
 
 // GetByHeight returns the FullCommit for height h or an error if the commit is not found.
 func (m *memStoreProvider) GetByHeight(h int64) (FullCommit, error) {
+	m.mtx.RLock()
+	defer m.mtx.RUnlock()
+
 	// search from highest to lowest
 	for i := len(m.byHeight) - 1; i >= 0; i-- {
 		fc := m.byHeight[i]
@@ -65,16 +73,21 @@ func (m *memStoreProvider) GetByHeight(h int64) (FullCommit, error) {
 
 // GetByHash returns the FullCommit for the hash or an error if the commit is not found.
 func (m *memStoreProvider) GetByHash(hash []byte) (FullCommit, error) {
-	var err error
+	m.mtx.RLock()
+	defer m.mtx.RUnlock()
+
 	fc, ok := m.byHash[m.encodeHash(hash)]
 	if !ok {
-		err = liteErr.ErrCommitNotFound()
+		return fc, liteErr.ErrCommitNotFound()
 	}
-	return fc, err
+	return fc, nil
 }
 
 // LatestCommit returns the latest FullCommit or an error if no commits exist.
 func (m *memStoreProvider) LatestCommit() (FullCommit, error) {
+	m.mtx.RLock()
+	defer m.mtx.RUnlock()
+
 	l := len(m.byHeight)
 	if l == 0 {
 		return FullCommit{}, liteErr.ErrCommitNotFound()