diff --git a/utbot-core/src/main/kotlin/org/utbot/common/FileUtil.kt b/utbot-core/src/main/kotlin/org/utbot/common/FileUtil.kt
index d0cee4777d..bb4936b8da 100644
--- a/utbot-core/src/main/kotlin/org/utbot/common/FileUtil.kt
+++ b/utbot-core/src/main/kotlin/org/utbot/common/FileUtil.kt
@@ -224,13 +224,16 @@ object FileUtil {
     }
 
     // https://stackoverflow.com/a/68822715
-    fun byteCountToDisplaySize(bytes: Long): String =
-        when {
-            bytes >= 1 shl 30 -> "%.1f GB".format(bytes / (1 shl 30))
-            bytes >= 1 shl 20 -> "%.1f MB".format(bytes / (1 shl 20))
-            bytes >= 1 shl 10 -> "%.0f kB".format(bytes / (1 shl 10))
-            else -> "$bytes bytes"
+    fun byteCountToDisplaySize(bytes: Long): String {
+        val bytesInDouble = bytes.toDouble()
+
+        return when {
+            bytesInDouble >= 1 shl 30 -> "%.1f GB".format(bytesInDouble / (1 shl 30))
+            bytesInDouble >= 1 shl 20 -> "%.1f MB".format(bytesInDouble / (1 shl 20))
+            bytesInDouble >= 1 shl 10 -> "%.0f kB".format(bytesInDouble / (1 shl 10))
+            else -> "$bytesInDouble bytes"
         }
+    }
 }
 
 /**
diff --git a/utbot-framework-test/src/test/kotlin/org/utbot/examples/lambda/PredicateNotExampleTest.kt b/utbot-framework-test/src/test/kotlin/org/utbot/examples/lambda/PredicateNotExampleTest.kt
new file mode 100644
index 0000000000..f57ac5359b
--- /dev/null
+++ b/utbot-framework-test/src/test/kotlin/org/utbot/examples/lambda/PredicateNotExampleTest.kt
@@ -0,0 +1,17 @@
+package org.utbot.examples.lambda
+
+import org.junit.jupiter.api.Test
+import org.utbot.testcheckers.eq
+import org.utbot.tests.infrastructure.UtValueTestCaseChecker
+
+class PredicateNotExampleTest : UtValueTestCaseChecker(testClass = PredicateNotExample::class) {
+    @Test
+    fun testPredicateNotExample() {
+        check(
+            PredicateNotExample::predicateNotExample,
+            eq(2),
+            { a, r -> a == 5 && r == false },
+            { a, r -> a != 5 && r == true },
+        )
+    }
+}
diff --git a/utbot-framework/src/main/kotlin/org/utbot/engine/TypeResolver.kt b/utbot-framework/src/main/kotlin/org/utbot/engine/TypeResolver.kt
index 64f950a83b..6ad34adc84 100644
--- a/utbot-framework/src/main/kotlin/org/utbot/engine/TypeResolver.kt
+++ b/utbot-framework/src/main/kotlin/org/utbot/engine/TypeResolver.kt
@@ -112,7 +112,7 @@ class TypeResolver(private val typeRegistry: TypeRegistry, private val hierarchy
                 if (numDimensions == 0) baseType else baseType.makeArrayType(numDimensions)
             }
 
-        return TypeStorage(type, concretePossibleTypes).filterInappropriateClassesForCodeGeneration()
+        return TypeStorage(type, concretePossibleTypes).removeInappropriateTypes()
     }
 
     private fun isInappropriateOrArrayOfMocksOrLocals(numDimensions: Int, baseType: Type?): Boolean {
@@ -182,46 +182,40 @@ class TypeResolver(private val typeRegistry: TypeRegistry, private val hierarchy
             else -> error("Unexpected type $type")
         }
 
-        return TypeStorage(type, possibleTypes).filterInappropriateClassesForCodeGeneration()
+        return TypeStorage(type, possibleTypes).removeInappropriateTypes()
     }
 
     /**
-     * Where possible, remove types that are not currently supported by code generation.
-     * For example, we filter out artificial entities (lambdas are an example of them)
-     * if the least common type is **not** artificial itself.
+     * Remove wrapper types and, if any other type is available, artificial entities.
      */
-    private fun TypeStorage.filterInappropriateClassesForCodeGeneration(): TypeStorage {
-        val unwantedTypes = mutableSetOf<Type>()
-        val concreteTypes = mutableSetOf<Type>()
-
+    private fun TypeStorage.removeInappropriateTypes(): TypeStorage {
         val leastCommonSootClass = (leastCommonType as? RefType)?.sootClass
         val keepArtificialEntities = leastCommonSootClass?.isArtificialEntity == true
 
-        possibleConcreteTypes.forEach {
-            val sootClass = (it.baseType as? RefType)?.sootClass ?: run {
-                // All not RefType should be included in the concreteTypes, e.g., arrays
-                concreteTypes += it
-                return@forEach
+        val appropriateTypes = possibleConcreteTypes.filter {
+            // All not RefType should be included in the concreteTypes, e.g., arrays
+            val sootClass = (it.baseType as? RefType)?.sootClass ?: return@filter true
+
+            // All artificial entities except anonymous functions should be filtered out if we have another types
+            if (sootClass.isArtificialEntity) {
+                if (sootClass.isLambda) {
+                    return@filter true
+                }
+
+                return@filter keepArtificialEntities
             }
-            when {
-                sootClass.isUtMock -> unwantedTypes += it
-                sootClass.isArtificialEntity -> {
-                    if (sootClass.isLambda) {
-                        unwantedTypes += it
-                    } else if (keepArtificialEntities) {
-                        concreteTypes += it
-                    }
+
+            // All wrappers should filtered out because they could not be instantiated
+            workaround(WorkaroundReason.HACK) {
+                if (leastCommonSootClass == OBJECT_TYPE && sootClass.isOverridden) {
+                    return@filter false
                 }
-                workaround(WorkaroundReason.HACK) { leastCommonSootClass == OBJECT_TYPE && sootClass.isOverridden } -> Unit
-                else -> concreteTypes += it
             }
-        }
 
-        return if (concreteTypes.isEmpty()) {
-            copy(possibleConcreteTypes = unwantedTypes)
-        } else {
-            copy(possibleConcreteTypes = concreteTypes)
-        }
+            return@filter true
+        }.toSet()
+
+        return copy(possibleConcreteTypes = appropriateTypes)
     }
 
     /**
diff --git a/utbot-sample/src/main/java/org/utbot/examples/lambda/PredicateNotExample.java b/utbot-sample/src/main/java/org/utbot/examples/lambda/PredicateNotExample.java
new file mode 100644
index 0000000000..3339750760
--- /dev/null
+++ b/utbot-sample/src/main/java/org/utbot/examples/lambda/PredicateNotExample.java
@@ -0,0 +1,13 @@
+package org.utbot.examples.lambda;
+
+import java.util.function.*;
+
+public class PredicateNotExample {
+    public boolean predicateNotExample(int a) {
+        if (Predicate.not(i -> i.equals(5)).test(a)) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+}