diff --git a/build.gradle b/build.gradle
index 516b94977..e36e841df 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,6 +1,6 @@
 plugins {
   id 'io.spinnaker.project' version "$spinnakerGradleVersion" apply false
-  id "nebula.kotlin" version "$kotlinVersion" apply false
+  id "org.jetbrains.kotlin.jvm" version "$kotlinVersion" apply false
   id "org.jetbrains.kotlin.plugin.allopen" version "$kotlinVersion" apply false
   id "org.jetbrains.dokka" version "0.10.1" apply false
 }
diff --git a/gate-core/src/main/groovy/com/netflix/spinnaker/gate/config/MultiAuthSupport.java b/gate-core/src/main/groovy/com/netflix/spinnaker/gate/config/MultiAuthSupport.java
index 983d7792a..15b79854c 100644
--- a/gate-core/src/main/groovy/com/netflix/spinnaker/gate/config/MultiAuthSupport.java
+++ b/gate-core/src/main/groovy/com/netflix/spinnaker/gate/config/MultiAuthSupport.java
@@ -1,6 +1,5 @@
 package com.netflix.spinnaker.gate.config;
 
-import com.netflix.spinnaker.config.TomcatConfigurationProperties;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.web.context.WebServerApplicationContext;
 import org.springframework.boot.web.embedded.tomcat.TomcatWebServer;
@@ -17,18 +16,18 @@ public class MultiAuthSupport {
   @Value("${default.legacy-server-port-auth:true}")
   private boolean legacyServerPortAuth;
 
+  @Value("${default.legacy-server-port:-1}")
+  private int legacyServerPort;
+
   @Bean
-  RequestMatcherProvider multiAuthRequestMatcherProvider(
-      ApplicationContext applicationContext,
-      TomcatConfigurationProperties tomcatConfigurationProperties) {
+  RequestMatcherProvider multiAuthRequestMatcherProvider(ApplicationContext applicationContext) {
     return new RequestMatcherProvider() {
       @Override
       public RequestMatcher requestMatcher() {
         if (applicationContext instanceof WebServerApplicationContext) {
           final WebServerApplicationContext ctx = (WebServerApplicationContext) applicationContext;
           return req -> {
-            if (legacyServerPortAuth
-                && tomcatConfigurationProperties.getLegacyServerPort() == req.getLocalPort()) {
+            if (legacyServerPortAuth && legacyServerPort == req.getLocalPort()) {
               return true;
             }
             // we have to do this per request because at bean-creation time the WebServer has not
diff --git a/gate-proxy/src/main/kotlin/com/netflix/spinnaker/gate/controllers/ApiExtensionController.kt b/gate-proxy/src/main/kotlin/com/netflix/spinnaker/gate/controllers/ApiExtensionController.kt
index 5a2e33c3c..da94b7641 100644
--- a/gate-proxy/src/main/kotlin/com/netflix/spinnaker/gate/controllers/ApiExtensionController.kt
+++ b/gate-proxy/src/main/kotlin/com/netflix/spinnaker/gate/controllers/ApiExtensionController.kt
@@ -48,7 +48,8 @@ class ApiExtensionController @Autowired constructor(private val apiExtensions: L
     val duplicateApiExtensionIds = apiExtensions
       .groupBy { it.id().toLowerCase() }
       .filter { it.value.size > 1 }
-      .flatMap { it.value }
+      .map { it.value }
+      .flatten()
       .map { "[class=${it.javaClass}], id=${it.id()}]" }
 
     if (duplicateApiExtensionIds.isNotEmpty()) {
diff --git a/gradle.properties b/gradle.properties
index 43253aca6..cd97d1401 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,8 +1,8 @@
 enablePublishing=false
 fiatVersion=1.22.0
 includeProviders=basic,iap,ldap,oauth2,saml,x509
-korkVersion=7.59.0
-kotlinVersion=1.3.71
+korkVersion=7.60.4
+kotlinVersion=1.4.0
 org.gradle.parallel=true
 spinnakerGradleVersion=8.5.0
 
diff --git a/gradle/kotlin-test.gradle b/gradle/kotlin-test.gradle
index ee5858c27..431af8313 100644
--- a/gradle/kotlin-test.gradle
+++ b/gradle/kotlin-test.gradle
@@ -38,7 +38,7 @@ test {
 
 compileTestKotlin {
   kotlinOptions {
-    languageVersion = "1.3"
+    languageVersion = "1.4"
     jvmTarget = "1.8"
   }
 }
diff --git a/gradle/kotlin.gradle b/gradle/kotlin.gradle
index e33aa76ef..6a3c31cf4 100644
--- a/gradle/kotlin.gradle
+++ b/gradle/kotlin.gradle
@@ -14,22 +14,20 @@
  * limitations under the License.
  */
 
-apply plugin: "nebula.kotlin"
+apply plugin: "kotlin"
 apply plugin: "kotlin-spring"
 
 compileKotlin {
   kotlinOptions {
-    languageVersion = "1.3"
+    languageVersion = "1.4"
     jvmTarget = "1.8"
-    freeCompilerArgs += ["-progressive"]
   }
 }
 
 compileTestKotlin {
   kotlinOptions {
-    languageVersion = "1.3"
+    languageVersion = "1.4"
     jvmTarget = "1.8"
-    freeCompilerArgs += ["-progressive"]
   }
 }