diff --git a/storage/db.go b/storage/db.go
index 297b84f..3fa5168 100644
--- a/storage/db.go
+++ b/storage/db.go
@@ -1,6 +1,11 @@
 package storage
 
-import "local/rproxy3/storage/packable"
+import (
+	"errors"
+	"local/rproxy3/storage/packable"
+)
+
+var ErrNotFound = errors.New("not found")
 
 type DB interface {
 	Get(string, string, packable.Packable) error
diff --git a/storage/map.go b/storage/map.go
index 29ce921..659795e 100644
--- a/storage/map.go
+++ b/storage/map.go
@@ -1,7 +1,6 @@
 package storage
 
 import (
-	"errors"
 	"fmt"
 	"local/rproxy3/storage/packable"
 )
@@ -46,7 +45,7 @@ func (m Map) Get(ns, key string, value packable.Packable) error {
 		m[ns] = make(map[string][]byte)
 	}
 	if _, ok := m[ns][key]; !ok {
-		return errors.New("not found")
+		return ErrNotFound
 	}
 	return value.Decode(m[ns][key])
 }
@@ -55,6 +54,12 @@ func (m Map) Set(ns, key string, value packable.Packable) error {
 	if _, ok := m[ns]; !ok {
 		m[ns] = make(map[string][]byte)
 	}
+	if value == nil {
+		if _, ok := m[ns][key]; ok {
+			delete(m[ns], key)
+		}
+		return nil
+	}
 	b, err := value.Encode()
 	if err != nil {
 		return err