diff --git a/build.gradle b/build.gradle
index 7f98138..1ea5ae6 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,7 +2,7 @@ group 'kotlin-in-action'
 version '1.0-SNAPSHOT'
 
 buildscript {
-    ext.kotlin_version = '1.1.2-2'
+    ext.kotlin_version = '1.6.21'
 
     repositories {
         mavenCentral()
@@ -19,9 +19,9 @@ repositories {
 }
 
 dependencies {
-    compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
-    compile "junit:junit:4.12"
+    compile 'junit:junit:4.13.2'
 }
 
 sourceSets {
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 6590ada..0fb0b99 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.1.1-all.zip
diff --git a/src/ch01/1.1_ATasteOfKotlin.kt b/src/ch01/1.1_ATasteOfKotlin.kt
index 404442c..57b3d6c 100755
--- a/src/ch01/1.1_ATasteOfKotlin.kt
+++ b/src/ch01/1.1_ATasteOfKotlin.kt
@@ -7,7 +7,7 @@ fun main(args: Array<String>) {
     val persons = listOf(Person("Alice"),
                          Person("Bob", age = 29))
 
-    val oldest = persons.maxBy { it.age ?: 0 }
+    val oldest = persons.maxByOrNull { it.age ?: 0 }
     println("The oldest is: $oldest")
 }
 
diff --git a/src/ch03/3.1_2_CreatingCollectionsInKotlin1.kt b/src/ch03/3.1_2_CreatingCollectionsInKotlin1.kt
index 0c4764e..83c2f3c 100755
--- a/src/ch03/3.1_2_CreatingCollectionsInKotlin1.kt
+++ b/src/ch03/3.1_2_CreatingCollectionsInKotlin1.kt
@@ -4,5 +4,5 @@ fun main(args: Array<String>) {
     val strings = listOf("first", "second", "fourteenth")
     println(strings.last())
     val numbers = setOf(1, 14, 2)
-    println(numbers.max())
+    println(numbers.maxOrNull())
 }
diff --git a/src/ch10/10.2.1_1_ReflectionAPI.kt b/src/ch10/10.2.1_1_ReflectionAPI.kt
index a701432..6d3e08b 100755
--- a/src/ch10/10.2.1_1_ReflectionAPI.kt
+++ b/src/ch10/10.2.1_1_ReflectionAPI.kt
@@ -1,6 +1,6 @@
 package ch10.ex2_1_1_ReflectionAPI
 
-import kotlin.reflect.memberProperties
+import kotlin.reflect.full.memberProperties
 
 class Person(val name: String, val age: Int)