diff --git a/src/jvm/main/org/jetbrains/kotlinx/lincheck/LinChecker.kt b/src/jvm/main/org/jetbrains/kotlinx/lincheck/LinChecker.kt
index 6f30b5ec7..a8b5ef56f 100644
--- a/src/jvm/main/org/jetbrains/kotlinx/lincheck/LinChecker.kt
+++ b/src/jvm/main/org/jetbrains/kotlinx/lincheck/LinChecker.kt
@@ -131,14 +131,7 @@ class LinChecker (private val testClass: Class<*>, options: Options<*, *>?) {
     }
 
     private fun ExecutionScenario.tryMinimize(threadId: Int, position: Int, testCfg: CTestConfiguration): LincheckFailure? {
-        var newScenario = this.copy()
-        val actors = newScenario[threadId] as MutableList<Actor>
-        actors.removeAt(position)
-        if (actors.isEmpty() && threadId != 0 && threadId != newScenario.threads + 1) {
-            // Also remove the empty thread
-            newScenario.parallelExecution.removeAt(threadId - 1)
-            newScenario = newScenario.setThreadIds()
-        }
+        val newScenario = this.copyWithRemovedActor(threadId, position)
         return if (newScenario.isValid) {
             newScenario.runTryMinimize(testCfg)
         } else null
@@ -175,13 +168,6 @@ class LinChecker (private val testClass: Class<*>, options: Options<*, *>?) {
         return result
     }
 
-    private fun List<Actor>.copyWithThreadId(threadId: Int) = map { actor -> actor.copyWithThreadId(threadId) }
-    private fun ExecutionScenario.setThreadIds() = ExecutionScenario(
-        initExecution,
-        parallelExecution.mapIndexed { index, actors -> actors.copyWithThreadId(index + 1) },
-        postExecution.copyWithThreadId(parallelExecution.size + 1)
-    )
-
     private fun ExecutionScenario.run(testCfg: CTestConfiguration, verifier: Verifier): LincheckFailure? =
         testCfg.createStrategy(
             testClass = testClass,
@@ -191,12 +177,6 @@ class LinChecker (private val testClass: Class<*>, options: Options<*, *>?) {
             verifier = verifier
         ).run()
 
-    private fun ExecutionScenario.copy() = ExecutionScenario(
-        ArrayList(initExecution),
-        parallelExecution.map { ArrayList(it) },
-        ArrayList(postExecution)
-    )
-
     private val ExecutionScenario.isValid: Boolean
         get() = !isParallelPartEmpty &&
                 (!hasSuspendableActors() || (!hasSuspendableActorsInInitPart && !hasPostPartAndSuspendableActors))
diff --git a/src/jvm/main/org/jetbrains/kotlinx/lincheck/execution/ExecutionScenario.java b/src/jvm/main/org/jetbrains/kotlinx/lincheck/execution/ExecutionScenario.kt
similarity index 50%
rename from src/jvm/main/org/jetbrains/kotlinx/lincheck/execution/ExecutionScenario.java
rename to src/jvm/main/org/jetbrains/kotlinx/lincheck/execution/ExecutionScenario.kt
index 7b5e02c79..cdcb2b2b9 100644
--- a/src/jvm/main/org/jetbrains/kotlinx/lincheck/execution/ExecutionScenario.java
+++ b/src/jvm/main/org/jetbrains/kotlinx/lincheck/execution/ExecutionScenario.kt
@@ -19,22 +19,17 @@
  * <http://www.gnu.org/licenses/lgpl-3.0.html>.
  * #L%
  */
-package org.jetbrains.kotlinx.lincheck.execution;
+package org.jetbrains.kotlinx.lincheck.execution
 
-import org.jetbrains.kotlinx.lincheck.Actor;
-import org.jetbrains.kotlinx.lincheck.strategy.Strategy;
-
-import java.util.*;
-import java.util.stream.*;
-
-import static org.jetbrains.kotlinx.lincheck.ReporterKt.appendExecutionScenario;
+import org.jetbrains.kotlinx.lincheck.Actor
+import org.jetbrains.kotlinx.lincheck.appendExecutionScenario
 
 /**
  * This class represents an execution scenario, which
  * is generated by an {@link ExecutionGenerator} and then \
  * used by a {@link Strategy} which produces an {@link ExecutionResult}.
  */
-public class ExecutionScenario {
+data class ExecutionScenario(
     /**
      * The initial sequential part of the execution.
      * It helps to produce different initial states
@@ -43,12 +38,12 @@ public class ExecutionScenario {
      * The initial execution part should contain only non-suspendable actors;
      * otherwise, the single initial execution thread will suspend with no chance to be resumed.
      */
-    public final List<Actor> initExecution;
+    val initExecution: List<Actor>,
     /**
      * The parallel part of the execution, which is used
      * to find an interleaving with incorrect behaviour.
      */
-    public final List<List<Actor>> parallelExecution;
+    val parallelExecution: List<List<Actor>>,
     /**
      * The last sequential part is used to test that
      * the data structure is in some correct state.
@@ -56,32 +51,53 @@ public class ExecutionScenario {
      * If this execution scenario contains suspendable actors, the post part should be empty;
      * if not, an actor could resume a previously suspended one from the parallel execution part.
      */
-    public final List<Actor> postExecution;
-
-    public ExecutionScenario(List<Actor> initExecution, List<List<Actor>> parallelExecution, List<Actor> postExecution) {
-        this.initExecution = initExecution;
-        this.parallelExecution = parallelExecution;
-        this.postExecution = postExecution;
-    }
+    val postExecution: List<Actor>
+) {
 
     /**
      * Returns the number of threads used in the parallel part of this execution.
      */
-    public int getThreads() {
-        return parallelExecution.size();
-    }
+    val threads get() = parallelExecution.size
 
     /**
      * Returns `true` if there is at least one suspendable actor in the generated scenario
      */
-    public boolean hasSuspendableActors() {
-        return Stream.concat(parallelExecution.stream().flatMap(Collection::stream), postExecution.stream()).anyMatch(Actor::isSuspendable);
-    }
+    fun hasSuspendableActors() = parallelExecution.asSequence().flatten().plus(postExecution).any(Actor::isSuspendable)
+
+
+    override fun toString() = StringBuilder()
+        .also { it.appendExecutionScenario(this) }
+        .toString()
 
-    @Override
-    public String toString() {
-        StringBuilder sb = new StringBuilder();
-        appendExecutionScenario(sb, this);
-        return sb.toString();
+    /**
+     * Copy the [ExecutionScenario] with the [actorId] actor of the [threadId] thread removed.
+     */
+    fun copyWithRemovedActor(threadId: Int, actorId: Int): ExecutionScenario = when (threadId) {
+        0 -> copy(initExecution = initExecution.removeAt(actorId))
+        in 1..threads -> {
+            val thread = parallelExecution[threadId - 1]
+            if (thread.size > 1) {
+                copy(parallelExecution = parallelExecution.mapIndexed { id, actors -> if (id == threadId - 1) actors.removeAt(actorId) else actors })
+            } else {
+                copy(
+                    parallelExecution = parallelExecution
+                        .removeAt(threadId - 1)
+                        .mapIndexed { id, actors -> actors.copyWithThreadId(id + 1) },
+                    postExecution = postExecution.copyWithThreadId(threads)
+                )
+            }
+        }
+        threads + 1 -> copy(postExecution = postExecution.removeAt(actorId))
+        else -> error("Thread id is out of bounds 0..${threads}: $threadId")
     }
 }
+
+/**
+ * Create a copy of the list without the [index] element.
+ */
+private fun <T> List<T>.removeAt(index: Int) = filterIndexed { i, _ -> i != index }
+
+/**
+ * Copy actors list with [threadId] set as thread id.
+ */
+private fun List<Actor>.copyWithThreadId(threadId: Int) = map { actor -> actor.copyWithThreadId(threadId) }