diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1c6bb3c0..5976805e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ '21' ]
+        java: [ '17', '21' ]
 
     steps:
       - uses: actions/checkout@v4
@@ -48,7 +48,7 @@ jobs:
       - uses: graalvm/setup-graalvm@v1
         with:
           version: 'latest'
-          java-version: '21'
+          java-version: '17'
           cache: 'gradle'
           github-token: ${{ secrets.GITHUB_TOKEN }}
       - name: Build with Gradle
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index ff13469a..9bb10c38 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -24,7 +24,7 @@ jobs:
         uses: actions/setup-java@v3
         with:
           distribution: 'zulu'
-          java-version: 21
+          java-version: 17
 
       - name: Checkout repository
         uses: actions/checkout@v4
diff --git a/Containerfile b/Containerfile
index 361c2667..1a1167ba 100644
--- a/Containerfile
+++ b/Containerfile
@@ -1,4 +1,4 @@
-FROM docker.io/azul/zulu-openjdk:21-jre-headless
+FROM docker.io/eclipse-temurin:17-jre
 
 LABEL org.opencontainers.image.source=https://github.com/AsamK/signal-cli
 LABEL org.opencontainers.image.description="signal-cli provides an unofficial commandline, dbus and JSON-RPC interface for the Signal messenger."
diff --git a/README.md b/README.md
index 6b87a745..a7676e07 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ Windows. There's also a [docker image and some Linux packages](https://github.co
 
 System requirements:
 
-- at least Java Runtime Environment (JRE) 21
+- at least Java Runtime Environment (JRE) 17
 - native library: libsignal-client
 
   The native libs are bundled for x86_64 Linux (with recent enough glibc), Windows and MacOS. For other
diff --git a/build.gradle.kts b/build.gradle.kts
index b65bce87..e0ff2632 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -9,12 +9,8 @@ plugins {
 version = "0.12.7"
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_21
-    targetCompatibility = JavaVersion.VERSION_21
-
-    toolchain {
-        languageVersion.set(JavaLanguageVersion.of(21))
-    }
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
 }
 
 application {
@@ -30,7 +26,7 @@ graalvmNative {
             if (System.getenv("GRAALVM_HOME") == null) {
                 toolchainDetection.set(true)
                 javaLauncher.set(javaToolchains.launcherFor {
-                    languageVersion.set(JavaLanguageVersion.of(21))
+                    languageVersion.set(JavaLanguageVersion.of(17))
                 })
             } else {
                 toolchainDetection.set(false)
diff --git a/graalvm-config-dir/reflect-config.json b/graalvm-config-dir/reflect-config.json
index 82f9c9c3..0186abfd 100644
--- a/graalvm-config-dir/reflect-config.json
+++ b/graalvm-config-dir/reflect-config.json
@@ -48,9 +48,6 @@
 {
   "name":"[Lorg.whispersystems.signalservice.internal.push.GroupStaleDevices;"
 },
-{
-  "name":"android.os.Build$VERSION"
-},
 {
   "name":"byte[]",
   "allDeclaredMethods":true,
diff --git a/graalvm-config-dir/resource-config.json b/graalvm-config-dir/resource-config.json
index 6902124a..e5fd25b2 100644
--- a/graalvm-config-dir/resource-config.json
+++ b/graalvm-config-dir/resource-config.json
@@ -28,8 +28,6 @@
     "pattern":"\\QMETA-INF/services/kotlin.reflect.jvm.internal.impl.resolve.ExternalOverridabilityCondition\\E"
   }, {
     "pattern":"\\QMETA-INF/services/kotlin.reflect.jvm.internal.impl.util.ModuleVisibilityHelper\\E"
-  }, {
-    "pattern":"\\QMETA-INF/services/org.freedesktop.dbus.spi.message.ISocketProvider\\E"
   }, {
     "pattern":"\\QMETA-INF/services/org.freedesktop.dbus.spi.transport.ITransportProvider\\E"
   }, {
@@ -202,8 +200,6 @@
     "pattern":"java.base:\\Qjdk/internal/icu/impl/data/icudt67b/nfc.nrm\\E"
   }, {
     "pattern":"java.base:\\Qjdk/internal/icu/impl/data/icudt67b/uprops.icu\\E"
-  }, {
-    "pattern":"java.base:\\Qjdk/internal/icu/impl/data/icudt72b/nfc.nrm\\E"
   }, {
     "pattern":"java.base:\\Qjdk/internal/icu/impl/data/icudt72b/uprops.icu\\E"
   }, {
diff --git a/lib/build.gradle.kts b/lib/build.gradle.kts
index c8f22f7c..93df49e7 100644
--- a/lib/build.gradle.kts
+++ b/lib/build.gradle.kts
@@ -4,12 +4,8 @@ plugins {
 }
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_21
-    targetCompatibility = JavaVersion.VERSION_21
-
-    toolchain {
-        languageVersion.set(JavaLanguageVersion.of(21))
-    }
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
 }
 
 val libsignalClientPath = project.findProperty("libsignal_client_path")?.toString()
diff --git a/run_tests.sh b/run_tests.sh
index 6a7c8358..ffec8b11 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -32,7 +32,7 @@ fi
 
 run() {
   # To update graalvm config, set GRAALVM_HOME, e.g:
-  # export GRAALVM_HOME=/usr/lib/jvm/java-21-graalvm
+  # export GRAALVM_HOME=/usr/lib/jvm/java-17-graalvm
   if [ ! -z "$GRAALVM_HOME" ]; then
     export JAVA_HOME=$GRAALVM_HOME
     export SIGNAL_CLI_OPTS="-agentlib:native-image-agent=config-merge-dir=graalvm-config-dir-${SIGNAL_CLI_AGENT_ID}/"