diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DefaultCryptoService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DefaultCryptoService.kt
index 61a072ece6..e37af45a73 100755
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DefaultCryptoService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DefaultCryptoService.kt
@@ -122,7 +122,8 @@ internal class DefaultCryptoService @Inject constructor(
         private val myDeviceInfoHolder: Lazy<MyDeviceInfoHolder>,
         // the crypto store
         private val cryptoStore: IMXCryptoStore,
-
+        // Room encryptors store
+        private val roomEncryptorsStore: RoomEncryptorsStore,
         // Olm device
         private val olmDevice: MXOlmDevice,
         // Set of parameters used to configure/customize the end-to-end crypto.
@@ -172,8 +173,6 @@ internal class DefaultCryptoService @Inject constructor(
 
     private val uiHandler = Handler(Looper.getMainLooper())
 
-    // MXEncrypting instance for each room.
-    private val roomEncryptors: MutableMap<String, IMXEncrypting> = HashMap()
     private val isStarting = AtomicBoolean(false)
     private val isStarted = AtomicBoolean(false)
 
@@ -512,9 +511,7 @@ internal class DefaultCryptoService @Inject constructor(
             else                      -> olmEncryptionFactory.create(roomId)
         }
 
-        synchronized(roomEncryptors) {
-            roomEncryptors.put(roomId, alg)
-        }
+        roomEncryptorsStore.put(roomId, alg)
 
         // if encryption was not previously enabled in this room, we will have been
         // ignoring new device events for these users so far. We may well have
@@ -596,16 +593,12 @@ internal class DefaultCryptoService @Inject constructor(
                 internalStart(false)
             }
             val userIds = getRoomUserIds(roomId)
-            var alg = synchronized(roomEncryptors) {
-                roomEncryptors[roomId]
-            }
+            var alg = roomEncryptorsStore.get(roomId)
             if (alg == null) {
                 val algorithm = getEncryptionAlgorithm(roomId)
                 if (algorithm != null) {
                     if (setEncryptionInRoom(roomId, algorithm, false, userIds)) {
-                        synchronized(roomEncryptors) {
-                            alg = roomEncryptors[roomId]
-                        }
+                        alg = roomEncryptorsStore.get(roomId)
                     }
                 }
             }
@@ -836,16 +829,8 @@ internal class DefaultCryptoService @Inject constructor(
      * @param event the membership event causing the change
      */
     private fun onRoomMembershipEvent(roomId: String, event: Event) {
-        val alg: IMXEncrypting?
+        roomEncryptorsStore.get(roomId) ?: /* No encrypting in this room */ return
 
-        synchronized(roomEncryptors) {
-            alg = roomEncryptors[roomId]
-        }
-
-        if (null == alg) {
-            // No encrypting in this room
-            return
-        }
         event.stateKey?.let { userId ->
             val roomMember: RoomMemberSummary? = event.content.toModel()
             val membership = roomMember?.membership
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/RoomEncryptorsStore.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/RoomEncryptorsStore.kt
new file mode 100644
index 0000000000..3b74e62167
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/RoomEncryptorsStore.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.matrix.android.internal.crypto
+
+import im.vector.matrix.android.internal.crypto.algorithms.IMXEncrypting
+import javax.inject.Inject
+
+internal class RoomEncryptorsStore @Inject constructor() {
+
+    // MXEncrypting instance for each room.
+    private val roomEncryptors = mutableMapOf<String, IMXEncrypting>()
+
+    fun put(roomId: String, alg: IMXEncrypting) {
+        synchronized(roomEncryptors) {
+            roomEncryptors.put(roomId, alg)
+        }
+    }
+
+    fun get(roomId: String): IMXEncrypting? {
+        return synchronized(roomEncryptors) {
+            roomEncryptors[roomId]
+        }
+    }
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt
index a2d21c4f89..0ce2269bde 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt
@@ -40,7 +40,7 @@ import timber.log.Timber
 
 internal class MXMegolmEncryption(
         // The id of the room we will be sending to.
-        private var roomId: String,
+        private val roomId: String,
         private val olmDevice: MXOlmDevice,
         private val defaultKeysBackupService: DefaultKeysBackupService,
         private val cryptoStore: IMXCryptoStore,