diff --git a/Makefile b/Makefile
index b70f9acc..0ba6414a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-VERSION=1.20.0
+VERSION=1.21.0
 
 default: versioncheck
 
diff --git a/README.md b/README.md
index 85368023..978c007e 100644
--- a/README.md
+++ b/README.md
@@ -113,8 +113,8 @@ scrape_configs:
 The docker images are available via:
 
 ```bash
-docker pull pambrose/prometheus-proxy:1.20.0
-docker pull pambrose/prometheus-agent:1.20.0
+docker pull pambrose/prometheus-proxy:1.21.0
+docker pull pambrose/prometheus-agent:1.21.0
 ```
 
 Start a proxy container with:
@@ -123,7 +123,7 @@ Start a proxy container with:
 docker run --rm -p 8082:8082 -p 8092:8092 -p 50051:50051 -p 8080:8080 \
         --env ADMIN_ENABLED=true \
         --env METRICS_ENABLED=true \
-        pambrose/prometheus-proxy:1.20.0
+        pambrose/prometheus-proxy:1.21.0
 ```
 
 Start an agent container with:
@@ -131,7 +131,7 @@ Start an agent container with:
 ```bash
 docker run --rm -p 8083:8083 -p 8093:8093 \
         --env AGENT_CONFIG='https://raw.githubusercontent.com/pambrose/prometheus-proxy/master/examples/simple.conf' \
-        pambrose/prometheus-agent:1.20.0
+        pambrose/prometheus-agent:1.21.0
 ```
 
 Using the config
@@ -149,7 +149,7 @@ is in your current directory, run an agent container with:
 docker run --rm -p 8083:8083 -p 8093:8093 \
     --mount type=bind,source="$(pwd)"/prom-agent.conf,target=/app/prom-agent.conf \
     --env AGENT_CONFIG=prom-agent.conf \
-    pambrose/prometheus-agent:1.20.0
+    pambrose/prometheus-agent:1.21.0
 ```
 
 **Note:** The `WORKDIR` of the proxy and agent images is `/app`, so make sure to use `/app` as the base directory in the
@@ -297,7 +297,7 @@ docker run --rm -p 8082:8082 -p 8092:8092 -p 50440:50440 -p 8080:8080 \
     --env PROXY_CONFIG=tls-no-mutual-auth.conf \
     --env ADMIN_ENABLED=true \
     --env METRICS_ENABLED=true \
-    pambrose/prometheus-proxy:1.20.0
+    pambrose/prometheus-proxy:1.21.0
 
 docker run --rm -p 8083:8083 -p 8093:8093 \
     --mount type=bind,source="$(pwd)"/testing/certs,target=/app/testing/certs \
@@ -305,7 +305,7 @@ docker run --rm -p 8083:8083 -p 8093:8093 \
     --env AGENT_CONFIG=tls-no-mutual-auth.conf \
     --env PROXY_HOSTNAME=mymachine.lan:50440 \
     --name docker-agent \
-    pambrose/prometheus-agent:1.20.0
+    pambrose/prometheus-agent:1.21.0
 ```
 
 **Note:** The `WORKDIR` of the proxy and agent images is `/app`, so make sure to use `/app` as the base directory in the
diff --git a/bin/docker-agent.sh b/bin/docker-agent.sh
index 3b7f9862..86323c63 100755
--- a/bin/docker-agent.sh
+++ b/bin/docker-agent.sh
@@ -3,4 +3,4 @@
 docker run --rm -p 8083:8083 -p 8093:8093 \
   --env AGENT_CONFIG='https://raw.githubusercontent.com/pambrose/prometheus-proxy/master/examples/simple.conf' \
   --env PROXY_HOSTNAME=mymachine.lan \
-  pambrose/prometheus-agent:1.20.0
+  pambrose/prometheus-agent:1.21.0
diff --git a/bin/docker-proxy.sh b/bin/docker-proxy.sh
index 7ca2c95f..0a6b562b 100755
--- a/bin/docker-proxy.sh
+++ b/bin/docker-proxy.sh
@@ -2,4 +2,4 @@
 
 docker run --rm -p 8082:8082 -p 8092:8092 -p 50051:50051 -p 8080:8080 \
   --env PROXY_CONFIG='https://raw.githubusercontent.com/pambrose/prometheus-proxy/master/examples/simple.conf' \
-  pambrose/prometheus-proxy:1.20.0
+  pambrose/prometheus-proxy:1.21.0
diff --git a/build.gradle b/build.gradle
index 3f7a7f7a..6d811fbd 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,12 +2,12 @@ plugins {
     id 'idea'
     id 'java'
     id 'maven-publish'
-    id 'org.jetbrains.kotlin.jvm' version '1.9.21'
+    id 'org.jetbrains.kotlin.jvm' version '1.9.22'
     id 'com.google.protobuf' version '0.9.4'   // Keep in sync with grpc
-    id 'org.jmailen.kotlinter' version "4.1.0"
+    id 'org.jmailen.kotlinter' version "4.1.1"
     id "com.github.ben-manes.versions" version '0.50.0'
     id 'com.github.johnrengelman.shadow' version '8.1.1'
-    id 'com.github.gmazzo.buildconfig' version '4.2.0'
+    id 'com.github.gmazzo.buildconfig' version '5.3.2'
     id 'org.jetbrains.kotlinx.kover' version '0.7.5'
     // Turn these off until jacoco fixes their kotlin 1.5.0 SMAP issue
     // id 'jacoco'
@@ -15,7 +15,7 @@ plugins {
 }
 
 group = 'io.prometheus'
-version = '1.20.0'
+version = '1.21.0'
 
 sourceCompatibility = JavaVersion.VERSION_17
 targetCompatibility = JavaVersion.VERSION_17
@@ -70,14 +70,14 @@ dependencies {
 
     implementation "io.prometheus:simpleclient:$prometheus_version"
 
-    implementation 'io.ktor:ktor-client-jvm:2.3.6'
-    implementation 'io.ktor:ktor-client-cio-jvm:2.3.6'
-    implementation 'io.ktor:ktor-client-auth-jvm:2.3.6'
-    implementation 'io.ktor:ktor-network-jvm:2.3.6'
-    implementation 'io.ktor:ktor-network-tls-jvm:2.3.6'
+    implementation "io.ktor:ktor-client-jvm:$ktor_version"
+    implementation "io.ktor:ktor-client-cio-jvm:$ktor_version"
+    implementation "io.ktor:ktor-client-auth-jvm:$ktor_version"
+    implementation "io.ktor:ktor-network-jvm:$ktor_version"
+    implementation "io.ktor:ktor-network-tls-jvm:$ktor_version"
 
-    implementation 'io.ktor:ktor-server-jvm:2.3.6'
-    implementation 'io.ktor:ktor-server-cio-jvm:2.3.6'
+    implementation "io.ktor:ktor-server-jvm:$ktor_version"
+    implementation "io.ktor:ktor-server-cio-jvm:$ktor_version"
     implementation "io.ktor:ktor-server-call-logging:$ktor_version"
     implementation "io.ktor:ktor-server-compression:$ktor_version"
 
diff --git a/etc/compose/proxy.yml b/etc/compose/proxy.yml
index f7988483..51158366 100644
--- a/etc/compose/proxy.yml
+++ b/etc/compose/proxy.yml
@@ -1,6 +1,6 @@
 prometheus-proxy:
   autoredeploy: true
-  image: 'pambrose/prometheus-proxy:1.20.0'
+  image: 'pambrose/prometheus-proxy:1.21.0'
   ports:
     - '8080:8080'
     - '8082:8082'
diff --git a/gradle.properties b/gradle.properties
index 333efe84..17b6c15e 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -11,14 +11,14 @@ org.gradle.jvmargs=-Xmx4096m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF
 annotation_version=1.3.2
 dropwizard_version=4.2.23
 gengrpc_version=1.4.1
-grpc_version=1.60.0
+grpc_version=1.60.1
 jcommander_version=1.82
-jetty_version=10.0.18
+jetty_version=10.0.19
 junit_version=5.10.1
 kluent_version=1.73
-kotlin_version=1.9.21
+kotlin_version=1.9.22
 krotodc_version=1.0.6
-ktor_version=2.3.6
+ktor_version=2.3.7
 logback_version=1.4.14
 logging_version=4.0.0-beta-2
 # Keep in sync with grpc
@@ -29,5 +29,5 @@ protoc_version=3.24.0
 serialization_version=1.6.2
 slf4j_version=2.0.9
 typesafe_version=1.4.3
-utils_version=1.43.0
-zipkin_version=5.16.0
+utils_version=1.44.0
+zipkin_version=5.17.1