diff --git a/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/MutablePsychomatrix.kt b/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/MutablePsychomatrix.kt
index 725f3c4..9844498 100644
--- a/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/MutablePsychomatrix.kt
+++ b/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/MutablePsychomatrix.kt
@@ -3,15 +3,18 @@ package com.github.insanusmokrassar.PsychomatrixBase.domain.entities
 import com.github.insanusmokrassar.PsychomatrixBase.domain.entities.operations.*
 import org.joda.time.DateTime
 
-class MutablePsychomatrix(date: DateTime) : Psychomatrix(date) {
+class MutablePsychomatrix private constructor(date: DateTime) : Psychomatrix(date) {
     private var mutableNumbers = calculateNumbers(date).toMutableList()
 
     override val numbers: ByteArray
         get() = mutableNumbers.toByteArray()
 
+    override val asMutablePsychomatrix: MutablePsychomatrix
+        get() = this
+
     private val mutableOperationsHistory: MutableList<Operation> = ArrayList()
 
-    constructor(psychomatrix: Psychomatrix): this(psychomatrix.date)
+    internal constructor(psychomatrix: Psychomatrix): this(psychomatrix.date)
 
     val operationsHistory: List<Operation>
         get() = mutableOperationsHistory
diff --git a/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/Psychomatrix.kt b/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/Psychomatrix.kt
index f88c2ad..3f7ddb2 100644
--- a/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/Psychomatrix.kt
+++ b/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/entities/Psychomatrix.kt
@@ -57,6 +57,10 @@ fun calculateNumbers(dateTime: DateTime): ByteArray {
 open class Psychomatrix(val date: DateTime) {
     protected open val numbers: ByteArray = calculateNumbers(date)
 
+    open val asMutablePsychomatrix: MutablePsychomatrix by lazy {
+        MutablePsychomatrix(this)
+    }
+
     /**
      * Always array 4*5 of values. In rows was put columns
      *
diff --git a/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/interactors/ModifyPsychomatrixUseCaseInteractor.kt b/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/interactors/ModifyPsychomatrixUseCaseInteractor.kt
index 280ab5c..0b9e871 100644
--- a/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/interactors/ModifyPsychomatrixUseCaseInteractor.kt
+++ b/src/main/kotlin/com/github/insanusmokrassar/PsychomatrixBase/domain/interactors/ModifyPsychomatrixUseCaseInteractor.kt
@@ -52,7 +52,7 @@ class ModifyPsychomatrixUseCaseInteractor : ModifyPsychomatrixUseCase {
     private fun asMutablePsychomatrix(psychomatrix: Psychomatrix): MutablePsychomatrix {
         return currentPsychomatrixes.firstOrNull {
             it == psychomatrix
-        } ?: (psychomatrix as? MutablePsychomatrix) ?: MutablePsychomatrix(psychomatrix).also {
+        } ?: psychomatrix.asMutablePsychomatrix.also {
             currentPsychomatrixes.add(it)
         }
     }