diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3f4070000..e234f3f9a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,7 +18,7 @@ jobs:
       # solution.
       fail-fast: false
       matrix:
-        kotlin-version: [1.3.72, 1.4.10, 1.4.20-RC]
+        kotlin-version: [1.4.10, 1.4.20-RC]
 
     steps:
       - uses: actions/checkout@v2
@@ -142,7 +142,7 @@ jobs:
       # solution.
       fail-fast: false
       matrix:
-        kotlin-version: [1.3.72, 1.4.10]
+        kotlin-version: [1.4.10]
 
     steps:
       - uses: actions/checkout@v2
diff --git a/annotations/build.gradle b/annotations/build.gradle
index 6d11f738b..69d3ec57d 100644
--- a/annotations/build.gradle
+++ b/annotations/build.gradle
@@ -1,6 +1,2 @@
 apply plugin: 'org.jetbrains.kotlin.jvm'
-apply plugin: 'com.vanniktech.maven.publish'
-
-dependencies {
-  implementation deps.kotlin.stdlib
-}
\ No newline at end of file
+apply plugin: 'com.vanniktech.maven.publish'
\ No newline at end of file
diff --git a/compiler/build.gradle b/compiler/build.gradle
index 02a94f5f1..f88b620b7 100644
--- a/compiler/build.gradle
+++ b/compiler/build.gradle
@@ -8,7 +8,6 @@ dependencies {
   implementation project(':annotations')
   implementation deps.dagger2.dagger
   implementation deps.jsr250
-  implementation deps.kotlin.stdlib
   implementation deps.kotlinpoet
 
   compileOnly deps.auto.service.annotations
@@ -31,13 +30,9 @@ if (rootProject.ext.kotlinIrSupported) {
 tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
   kotlinOptions {
     jvmTarget = JavaVersion.VERSION_1_8
-    freeCompilerArgs += "-Xopt-in=kotlin.RequiresOptIn"
-
-    // TODO: remove the if-check when upgrading to Kotlin 1.4.
-    if (rootProject.ext.kotlinVersion.startsWith('1.4')) {
-      // The flag is needed because we extend an interface that uses @JvmDefault and the Kotlin
-      // compiler requires this flag when doing so.
-      freeCompilerArgs += "-Xjvm-default=enable"
-    }
+
+    // The flag is needed because we extend an interface that uses @JvmDefault and the Kotlin
+    // compiler requires this flag when doing so.
+    freeCompilerArgs += "-Xjvm-default=enable"
   }
 }
diff --git a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/BindingModuleGenerator.kt b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/BindingModuleGenerator.kt
index df5b5f8c3..8f78810cc 100644
--- a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/BindingModuleGenerator.kt
+++ b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/BindingModuleGenerator.kt
@@ -145,7 +145,6 @@ internal class BindingModuleGenerator(
         .toList()
   }
 
-  @OptIn(ExperimentalStdlibApi::class)
   override fun flush(
     codeGenDir: File,
     module: ModuleDescriptor
diff --git a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/KotlinPoet.kt b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/KotlinPoet.kt
index ecb7038df..6ac48203f 100644
--- a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/KotlinPoet.kt
+++ b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/KotlinPoet.kt
@@ -249,21 +249,11 @@ internal fun <T : KtCallableDeclaration> TypeName.withJvmSuppressWildcardsIfNeed
 
   return when {
     hasJvmSuppressWildcards || isGenericType -> this.jvmSuppressWildcards()
-    isFunctionType -> this.jvmSuppressWildcardsKt31734()
+    isFunctionType -> this.jvmSuppressWildcards()
     else -> this
   }
 }
 
-// TODO: remove with Kotlin 1.4.
-// Notice the empty member. Instead of generating `@JvmSuppressWildcards Type` it generates
-// `@JvmSuppressWildcards() Type`. This is necessary to avoid KT-31734 where the type is a function.
-private fun TypeName.jvmSuppressWildcardsKt31734() =
-  copy(
-      annotations = this.annotations + AnnotationSpec.builder(JvmSuppressWildcards::class)
-          .addMember("")
-          .build()
-  )
-
 internal fun List<Parameter>.asArgumentList(
   asProvider: Boolean,
   includeModule: Boolean
diff --git a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/InjectConstructorFactoryGenerator.kt b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/InjectConstructorFactoryGenerator.kt
index 7d9bdf433..5c0070186 100644
--- a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/InjectConstructorFactoryGenerator.kt
+++ b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/InjectConstructorFactoryGenerator.kt
@@ -50,7 +50,6 @@ internal class InjectConstructorFactoryGenerator : PrivateCodeGenerator() {
         }
   }
 
-  @OptIn(ExperimentalStdlibApi::class)
   private fun generateFactoryClass(
     codeGenDir: File,
     module: ModuleDescriptor,
@@ -60,7 +59,7 @@ internal class InjectConstructorFactoryGenerator : PrivateCodeGenerator() {
     val packageName = clazz.containingKtFile.packageFqName.asString()
     val className = "${clazz.generateClassName()}_Factory"
 
-    val parameters = constructor.getValueParameters().mapToParameter(module)
+    val parameters = constructor.valueParameters.mapToParameter(module)
 
     val typeParameters = clazz.typeParameterList
       ?.parameters
diff --git a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/MembersInjectorGenerator.kt b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/MembersInjectorGenerator.kt
index a4d5e6fb9..b07b5d3db 100644
--- a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/MembersInjectorGenerator.kt
+++ b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/MembersInjectorGenerator.kt
@@ -61,7 +61,6 @@ internal class MembersInjectorGenerator : PrivateCodeGenerator() {
         }
   }
 
-  @OptIn(ExperimentalStdlibApi::class)
   private fun generateMembersInjectorClass(
     codeGenDir: File,
     module: ModuleDescriptor,
diff --git a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/ProvidesMethodFactoryGenerator.kt b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/ProvidesMethodFactoryGenerator.kt
index 5a91c36c2..7c86c7387 100644
--- a/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/ProvidesMethodFactoryGenerator.kt
+++ b/compiler/src/main/java/com/squareup/anvil/compiler/codegen/dagger/ProvidesMethodFactoryGenerator.kt
@@ -90,7 +90,6 @@ internal class ProvidesMethodFactoryGenerator : PrivateCodeGenerator() {
         }
   }
 
-  @OptIn(ExperimentalStdlibApi::class)
   private fun generateFactoryClass(
     codeGenDir: File,
     module: ModuleDescriptor,
diff --git a/compiler/src/test/java/com/squareup/anvil/compiler/TestUtils.kt b/compiler/src/test/java/com/squareup/anvil/compiler/TestUtils.kt
index 946a966df..0d4c48cf0 100644
--- a/compiler/src/test/java/com/squareup/anvil/compiler/TestUtils.kt
+++ b/compiler/src/test/java/com/squareup/anvil/compiler/TestUtils.kt
@@ -116,14 +116,12 @@ internal val Result.innerModule: Class<*>
 internal val Result.injectClass: Class<*>
   get() = classLoader.loadClass("com.squareup.test.InjectClass")
 
-@OptIn(ExperimentalStdlibApi::class)
 internal val Class<*>.hintContributes: KClass<*>?
   get() = contributedProperties(HINT_CONTRIBUTES_PACKAGE_PREFIX)
       ?.filter { it.java == this }
       ?.also { assertThat(it.size).isEqualTo(1) }
       ?.first()
 
-@OptIn(ExperimentalStdlibApi::class)
 internal val Class<*>.hintContributesScope: KClass<*>?
   get() = contributedProperties(HINT_CONTRIBUTES_PACKAGE_PREFIX)
       ?.also { assertThat(it.size).isEqualTo(2) }
@@ -131,14 +129,12 @@ internal val Class<*>.hintContributesScope: KClass<*>?
       ?.also { assertThat(it.size).isEqualTo(1) }
       ?.first()
 
-@OptIn(ExperimentalStdlibApi::class)
 internal val Class<*>.hintBinding: KClass<*>?
   get() = contributedProperties(HINT_BINDING_PACKAGE_PREFIX)
       ?.filter { it.java == this }
       ?.also { assertThat(it.size).isEqualTo(1) }
       ?.first()
 
-@OptIn(ExperimentalStdlibApi::class)
 internal val Class<*>.hintBindingScope: KClass<*>?
   get() = contributedProperties(HINT_BINDING_PACKAGE_PREFIX)
       ?.also { assertThat(it.size).isEqualTo(2) }
@@ -146,7 +142,6 @@ internal val Class<*>.hintBindingScope: KClass<*>?
       ?.also { assertThat(it.size).isEqualTo(1) }
       ?.first()
 
-@OptIn(ExperimentalStdlibApi::class)
 internal fun Class<*>.moduleFactoryClass(
   providerMethodName: String,
   companion: Boolean = false
@@ -160,14 +155,12 @@ internal fun Class<*>.moduleFactoryClass(
   )
 }
 
-@OptIn(ExperimentalStdlibApi::class)
 internal fun Class<*>.factoryClass(): Class<*> {
   val enclosingClassString = enclosingClass?.let { "${it.simpleName}_" } ?: ""
 
   return classLoader.loadClass("${`package`.name}.$enclosingClassString${simpleName}_Factory")
 }
 
-@OptIn(ExperimentalStdlibApi::class)
 internal fun Class<*>.membersInjector(): Class<*> {
   val enclosingClassString = enclosingClass?.let { "${it.simpleName}_" } ?: ""
 
@@ -175,7 +168,6 @@ internal fun Class<*>.membersInjector(): Class<*> {
       "$enclosingClassString${simpleName}_MembersInjector")
 }
 
-@OptIn(ExperimentalStdlibApi::class)
 private fun Class<*>.contributedProperties(packagePrefix: String): List<KClass<*>>? {
   // The capitalize() doesn't make sense, I don't know where this is coming from. Maybe it's a
   // bug in the compile testing library?
diff --git a/compiler/src/test/java/com/squareup/anvil/compiler/dagger/MembersInjectorGeneratorTest.kt b/compiler/src/test/java/com/squareup/anvil/compiler/dagger/MembersInjectorGeneratorTest.kt
index 8c89b9eaa..ef0ea2cea 100644
--- a/compiler/src/test/java/com/squareup/anvil/compiler/dagger/MembersInjectorGeneratorTest.kt
+++ b/compiler/src/test/java/com/squareup/anvil/compiler/dagger/MembersInjectorGeneratorTest.kt
@@ -166,6 +166,7 @@ public final class InjectClass_MembersInjector implements MembersInjector<Inject
               Provider::class.java, Provider::class.java
           )
 
+      @Suppress("RedundantLambdaArrow")
       val membersInjectorInstance = constructor
           .newInstance(
               Provider { "a" }, Provider<CharSequence> { "b" }, Provider { listOf("c") },
@@ -675,7 +676,6 @@ public final class InjectClass_MembersInjector<T, U, V> implements MembersInject
     }
   }
 
-  @OptIn(ExperimentalStdlibApi::class)
   private fun Class<*>.staticInjectMethod(memberName: String): Method {
     // We can't check the @InjectedFieldSignature annotation unfortunately, because it has class
     // retention.
diff --git a/dependencies.gradle b/dependencies.gradle
index c1047b4db..e9f385219 100644
--- a/dependencies.gradle
+++ b/dependencies.gradle
@@ -5,7 +5,7 @@ ext {
   daggerVersion = '2.28'
   espressoVersion = '3.2.0'
   kotlinVersion = project.hasProperty('square.kotlinVersion') ?
-      project.getProperty('square.kotlinVersion') : '1.3.72'
+      project.getProperty('square.kotlinVersion') : '1.4.10'
 
   kotlinUseIR = (project.hasProperty('square.useIR') ?
       project.getProperty('square.useIR') : 'false').toBoolean()
@@ -70,6 +70,13 @@ ext {
           stdlib: "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlinVersion",
       ],
 
+      // Required until Gradle uses Kotlin 1.4.
+      kotlin_gradle: [
+          gradle_plugin: "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.72",
+          gradle_plugin_api: "org.jetbrains.kotlin:kotlin-gradle-plugin-api:1.3.72",
+          stdlib: "org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.72",
+      ],
+
       kotlinpoet: "com.squareup:kotlinpoet:1.7.2",
 
       truth: "com.google.truth:truth:1.0.1",
diff --git a/gradle-plugin/build.gradle b/gradle-plugin/build.gradle
index aa878ac15..d57ef769a 100644
--- a/gradle-plugin/build.gradle
+++ b/gradle-plugin/build.gradle
@@ -15,7 +15,7 @@ buildscript {
   }
 
   dependencies {
-    classpath deps.kotlin.gradle_plugin
+    classpath deps.kotlin_gradle.gradle_plugin
     classpath deps.maven_publishing_plugin
     classpath deps.gradle_publishing_plugin
     classpath deps.ktlint_plugin
@@ -76,9 +76,9 @@ tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
 }
 
 dependencies {
-  implementation deps.kotlin.gradle_plugin
-  implementation deps.kotlin.gradle_plugin_api
-  implementation deps.kotlin.stdlib
+  implementation deps.kotlin_gradle.gradle_plugin
+  implementation deps.kotlin_gradle.gradle_plugin_api
+  implementation deps.kotlin_gradle.stdlib
 
   // Compile only so that Java / Kotlin modules don't download it unnecessarily.
   compileOnly deps.android_gradle_plugin
diff --git a/gradle-plugin/gradle/wrapper/gradle-wrapper.properties b/gradle-plugin/gradle/wrapper/gradle-wrapper.properties
index 33682bbbf..4d9ca1649 100644
--- a/gradle-plugin/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle-plugin/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.6.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 33682bbbf..4d9ca1649 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.6.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/integration-tests/library/build.gradle b/integration-tests/library/build.gradle
index f779b75ed..87f5f6b46 100644
--- a/integration-tests/library/build.gradle
+++ b/integration-tests/library/build.gradle
@@ -15,7 +15,6 @@ if (rootProject.ext.generateDaggerFactoriesWithAnvil) {
 
 dependencies {
   api deps.dagger2.dagger
-  api deps.kotlin.stdlib
 }
 
 //noinspection UnnecessaryQualifiedReference
diff --git a/integration-tests/tests/build.gradle b/integration-tests/tests/build.gradle
index 073818e66..7d78c65ee 100644
--- a/integration-tests/tests/build.gradle
+++ b/integration-tests/tests/build.gradle
@@ -8,7 +8,6 @@ dependencies {
   testImplementation project(':integration-tests:library')
   testImplementation deps.dagger2.dagger
   testImplementation deps.junit
-  testImplementation deps.kotlin.stdlib
   testImplementation deps.truth
 
   kaptTest deps.dagger2.compiler
diff --git a/sample/app/build.gradle b/sample/app/build.gradle
index 43f5478d7..3e5c6e529 100644
--- a/sample/app/build.gradle
+++ b/sample/app/build.gradle
@@ -39,7 +39,6 @@ dependencies {
   implementation project(':sample:library')
   implementation project(':sample:scopes')
 
-  implementation deps.kotlin.stdlib
   implementation deps.androidx.appcompat
   implementation deps.androidx.core
   implementation deps.androidx.material
diff --git a/sample/library/build.gradle b/sample/library/build.gradle
index 014f4477f..51da41db5 100644
--- a/sample/library/build.gradle
+++ b/sample/library/build.gradle
@@ -16,12 +16,4 @@ if (rootProject.ext.generateDaggerFactoriesWithAnvil) {
 dependencies {
   api project(':sample:scopes')
   api deps.dagger2.dagger
-  api deps.kotlin.stdlib
-}
-
-//noinspection UnnecessaryQualifiedReference
-tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
-  kotlinOptions {
-    freeCompilerArgs += "-Xopt-in=kotlin.RequiresOptIn"
-  }
 }
diff --git a/sample/library/src/main/java/com/squareup/anvil/sample/Description.kt b/sample/library/src/main/java/com/squareup/anvil/sample/Description.kt
index a20e1fef7..749528caa 100644
--- a/sample/library/src/main/java/com/squareup/anvil/sample/Description.kt
+++ b/sample/library/src/main/java/com/squareup/anvil/sample/Description.kt
@@ -6,7 +6,6 @@ import com.squareup.scopes.ComponentHolder
 import java.util.Locale
 
 object Description {
-  @OptIn(ExperimentalStdlibApi::class)
   fun of(god: God): String {
     val name = god.name.toLowerCase(Locale.US)
         .capitalize(Locale.US)
@@ -16,12 +15,8 @@ object Description {
       MOTHER -> "daughter"
     }
 
-    return "$name, $child of ${
-      ComponentHolder.component<DescriptionComponent>()
-          .fatherProvider()
-        .father(god)} and ${
-      ComponentHolder.component<DescriptionComponent>()
-          .motherProvider()
-        .mother(god)}"
+    return "$name, $child of " +
+        "${ComponentHolder.component<DescriptionComponent>().fatherProvider().father(god)} and " +
+        ComponentHolder.component<DescriptionComponent>().motherProvider().mother(god)
   }
 }
diff --git a/sample/scopes/build.gradle b/sample/scopes/build.gradle
index 62ab6e9b3..d32997f6c 100644
--- a/sample/scopes/build.gradle
+++ b/sample/scopes/build.gradle
@@ -1,6 +1,5 @@
 apply plugin: 'org.jetbrains.kotlin.jvm'
 
 dependencies {
-  api deps.kotlin.stdlib
   api deps.inject
 }
\ No newline at end of file