diff --git a/pkg/engine/inmemory/local_storage.go b/pkg/engine/inmemory/local_storage.go
index 4055657..21d3d55 100644
--- a/pkg/engine/inmemory/local_storage.go
+++ b/pkg/engine/inmemory/local_storage.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math/rand"
 	"strings"
+	"sync"
 
 	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
 	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/engine"
@@ -15,12 +16,14 @@ type targetToChain map[engine.Target][]*chain.Chain
 type inmemoryLocalStorage struct {
 	usedChainID          map[chain.ID]struct{}
 	nameToResourceChains map[chain.Name]targetToChain
+	guard                *sync.RWMutex
 }
 
 func NewInmemoryLocalStorage() engine.LocalOverrideStorage {
 	return &inmemoryLocalStorage{
 		usedChainID:          map[chain.ID]struct{}{},
 		nameToResourceChains: make(map[chain.Name]targetToChain),
+		guard:                &sync.RWMutex{},
 	}
 }
 
@@ -44,6 +47,9 @@ func (s *inmemoryLocalStorage) generateChainID(name chain.Name, target engine.Ta
 }
 
 func (s *inmemoryLocalStorage) AddOverride(name chain.Name, target engine.Target, c *chain.Chain) (chain.ID, error) {
+	s.guard.Lock()
+	defer s.guard.Unlock()
+
 	// AddOverride assigns generated chain ID if it has not been assigned.
 	if c.ID == "" {
 		c.ID = s.generateChainID(name, target)
@@ -63,6 +69,9 @@ func (s *inmemoryLocalStorage) AddOverride(name chain.Name, target engine.Target
 }
 
 func (s *inmemoryLocalStorage) GetOverride(name chain.Name, target engine.Target, chainID chain.ID) (*chain.Chain, error) {
+	s.guard.RLock()
+	defer s.guard.RUnlock()
+
 	if _, ok := s.nameToResourceChains[name]; !ok {
 		return nil, engine.ErrChainNameNotFound
 	}
@@ -79,6 +88,9 @@ func (s *inmemoryLocalStorage) GetOverride(name chain.Name, target engine.Target
 }
 
 func (s *inmemoryLocalStorage) RemoveOverride(name chain.Name, target engine.Target, chainID chain.ID) error {
+	s.guard.Lock()
+	defer s.guard.Unlock()
+
 	if _, ok := s.nameToResourceChains[name]; !ok {
 		return engine.ErrChainNameNotFound
 	}
@@ -96,6 +108,9 @@ func (s *inmemoryLocalStorage) RemoveOverride(name chain.Name, target engine.Tar
 }
 
 func (s *inmemoryLocalStorage) ListOverrides(name chain.Name, target engine.Target) ([]*chain.Chain, error) {
+	s.guard.RLock()
+	defer s.guard.RUnlock()
+
 	rcs, ok := s.nameToResourceChains[name]
 	if !ok {
 		return []*chain.Chain{}, nil
@@ -113,6 +128,9 @@ func (s *inmemoryLocalStorage) ListOverrides(name chain.Name, target engine.Targ
 }
 
 func (s *inmemoryLocalStorage) DropAllOverrides(name chain.Name) error {
+	s.guard.Lock()
+	defer s.guard.Unlock()
+
 	s.nameToResourceChains[name] = make(targetToChain)
 	return nil
 }