diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index d05624c..61067d8 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -15,13 +15,13 @@ jobs:
       fail-fast: false
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4.1.1
 
-      - uses: actions/setup-java@v3
+      - uses: actions/setup-java@v4.0.0
         with:
           distribution: zulu
           java-version: ${{ matrix.java }}
 
-      - uses: gradle/gradle-build-action@v2
+      - uses: gradle/gradle-build-action@v2.12.0
         with:
           arguments: build
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d291d43..0c65b88 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,17 @@ marytts-voicebuilding
 [Unreleased]
 ------------
 
+### Fixed
+
+- Replaced dead repo for JTok dependency
+
+### Changed
+
+- Build with Gradle v8.6
+- Upgraded GitHub actions
+- Upgraded dependencies
+- Upgraded plugins
+
 [v0.2.1] (2023-01-11)
 ---------------------
 
diff --git a/build.gradle b/build.gradle
index 517db62..f4b3344 100644
--- a/build.gradle
+++ b/build.gradle
@@ -28,7 +28,7 @@ repositories {
     exclusiveContent {
         forRepository {
             maven {
-                url 'https://mlt.jfrog.io/artifactory/mlt-mvn-releases-local'
+                url 'https://raw.githubusercontent.com/DFKI-MLT/Maven-Repository/main'
             }
         }
         filter {
@@ -43,7 +43,7 @@ dependencies {
         exclude group: 'gov.nist.math', module: 'Jampack'
     }
     runtimeOnly group: 'xerces', name: 'xercesImpl', version: '2.12.2'
-    testImplementation group: 'org.testng', name: 'testng', version: '7.5'
+    testImplementation group: 'org.testng', name: 'testng', version: '7.5.1'
     testImplementation group: 'xmlunit', name: 'xmlunit', version: '1.6'
     testRuntimeOnly group: 'de.dfki.mary', name: 'voice-cmu-slt-hsmm', version: libs.versions.marytts.get(), {
         transitive = false
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 249e583..d64cd49 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index ae04661..a80b22c 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index a69d9cb..1aa94a4 100755
--- a/gradlew
+++ b/gradlew
@@ -55,7 +55,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +80,11 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -133,22 +131,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,11 +198,15 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
diff --git a/gradlew.bat b/gradlew.bat
index f127cfd..25da30d 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -26,6 +26,7 @@ if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
 if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -42,11 +43,11 @@ set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
 if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -56,11 +57,11 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
diff --git a/settings.gradle b/settings.gradle
index 24ca682..1568c81 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,4 +1,9 @@
+plugins {
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '0.8.0'
+}
+
 rootProject.name = 'marytts-voicebuilding'
+
 dependencyResolutionManagement {
     versionCatalogs {
         libs {