diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9ce6bad20b..2490cd1df0 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -17,24 +17,26 @@ env:
 
 jobs:
   build:
-    name: "Build on JDK ${{ matrix.java }}"
+    name: "Build on JDK ${{ matrix.java }} (${{ matrix.java-package }})"
     strategy:
       matrix:
-        java: [ 17, 21 ]
+        java: [ 17, 21, 25 ]
+        java-package: [ jdk ]
         include:
           # Custom JDK 11 configuration because some of the plugins and test dependencies don't support it anymore,
           # but it is important to still test with a JDK version without Record classes
           - java: 11
+            java-package: jdk
             # Disable Enforcer check which (intentionally) prevents using JDK 11 for building
             # Exclude 'test-graal-native-image' module because JUnit 6 requires >= Java 17
             # Exclude 'proto' module because protobuf-maven-plugin requires >= Java 17
             extra-mvn-args: -Denforcer.fail=false --projects '!test-graal-native-image,!proto'
+          # Additional build with JDK 25 and jmod files, to run ProGuard-related tests on JDK 25 as well
+          # Not needed for older JDK versions tested here, they include jmod files by default
+          # See also https://github.com/Guardsquare/proguard/issues/473
+          # TODO: Remove this and the `java-package` config once ProGuard does not require jmod files anymore
           - java: 25
-            # Disable Enforcer check which (intentionally) prevents using JDK 25 for building
-            # Exclude 'test-shrinker' because ProGuard does not support JDK 25 yet, see
-            # https://github.com/Guardsquare/proguard/issues/481 and https://github.com/Guardsquare/proguard/issues/473
-            # TODO: Once ProGuard supports JDK 25, also remove the corresponding 'JDK25' profile in `gson/pom.xml`
-            extra-mvn-args: -Denforcer.fail=false --projects '!test-shrinker'
+            java-package: jdk+jmods
     runs-on: ubuntu-latest
 
     steps:
@@ -42,10 +44,11 @@ jobs:
         with:
           persist-credentials: false
       - name: "Set up JDK ${{ matrix.java }}"
-        uses: actions/setup-java@03ad4de0992f5dab5e18fcb136590ce7c4a0ac95  # v5.6.0
+        uses: actions/setup-java@dd06d9cba3e5552c54d9f8ea23572deb30010f7c  # v6.0.0
         with:
           distribution: 'temurin'
           java-version: ${{ matrix.java }}
+          java-package: ${{ matrix.java-package }}
           cache: 'maven'
       - name: Build with Maven
         # This also runs javadoc:jar to detect any issues with the Javadoc generated during release
@@ -60,7 +63,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Set up JDK
-        uses: actions/setup-java@03ad4de0992f5dab5e18fcb136590ce7c4a0ac95  # v5.6.0
+        uses: actions/setup-java@dd06d9cba3e5552c54d9f8ea23572deb30010f7c  # v6.0.0
         with:
           distribution: 'temurin'
           java-version: 21
@@ -72,12 +75,7 @@ jobs:
     name: "GraalVM Native Image test (JDK ${{ matrix.java }})"
     strategy:
       matrix:
-        java: [ 21 ]
-        include:
-          - java: 25
-            # Disable Enforcer check which (intentionally) prevents using JDK 25 for building
-            # TODO: Remove this once JDK 25 is fully supported for building Gson
-            extra-mvn-args: -Denforcer.fail=false
+        java: [ 21, 25 ]
     runs-on: ubuntu-latest
 
     steps:
@@ -106,7 +104,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Set up JDK
-        uses: actions/setup-java@03ad4de0992f5dab5e18fcb136590ce7c4a0ac95  # v5.6.0
+        uses: actions/setup-java@dd06d9cba3e5552c54d9f8ea23572deb30010f7c  # v6.0.0
         with:
           distribution: 'temurin'
           java-version: 17
diff --git a/.github/workflows/check-android-compatibility.yml b/.github/workflows/check-android-compatibility.yml
index a3f02ab6a6..d650ac7541 100644
--- a/.github/workflows/check-android-compatibility.yml
+++ b/.github/workflows/check-android-compatibility.yml
@@ -29,7 +29,7 @@ jobs:
           persist-credentials: false
 
       - name: Set up JDK
-        uses: actions/setup-java@03ad4de0992f5dab5e18fcb136590ce7c4a0ac95  # v5.6.0
+        uses: actions/setup-java@dd06d9cba3e5552c54d9f8ea23572deb30010f7c  # v6.0.0
         with:
           distribution: 'temurin'
           java-version: '17'
diff --git a/.github/workflows/check-api-compatibility.yml b/.github/workflows/check-api-compatibility.yml
index 6c10ddec71..708194bb14 100644
--- a/.github/workflows/check-api-compatibility.yml
+++ b/.github/workflows/check-api-compatibility.yml
@@ -32,7 +32,7 @@ jobs:
           persist-credentials: false
 
       - name: Set up JDK
-        uses: actions/setup-java@03ad4de0992f5dab5e18fcb136590ce7c4a0ac95  # v5.6.0
+        uses: actions/setup-java@dd06d9cba3e5552c54d9f8ea23572deb30010f7c  # v6.0.0
         with:
           distribution: 'temurin'
           java-version: '17'
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index 90e1143f6a..b310b14385 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -43,7 +43,7 @@ jobs:
 
     - name: Set up JDK
       if: ${{ matrix.language == 'java' }}
-      uses: actions/setup-java@03ad4de0992f5dab5e18fcb136590ce7c4a0ac95  # v5.6.0
+      uses: actions/setup-java@dd06d9cba3e5552c54d9f8ea23572deb30010f7c  # v6.0.0
       with:
         distribution: 'temurin'
         java-version: '17'
diff --git a/README.md b/README.md
index 55ed4c8a99..6499af807f 100644
--- a/README.md
+++ b/README.md
@@ -95,7 +95,7 @@ Gson uses Maven to build the project:
 mvn clean verify
 ```
 
-JDK 17 or newer is required for building, JDK 21 is recommended. Newer JDKs are currently not supported for building (but are supported when _using_ Gson).
+JDK 17 or newer is required for building, JDK 21 is recommended. JDK 25 is supported, but only runs a subset of all tests if JDK `jmod` files are missing. Newer JDKs are currently not supported for building (but are supported when _using_ Gson).
 
 ### Contributing
 
diff --git a/gson/pom.xml b/gson/pom.xml
index 582fc200d8..af323b9769 100644
--- a/gson/pom.xml
+++ b/gson/pom.xml
@@ -353,8 +353,9 @@
   </build>
 
   <profiles>
+    <!-- Profile for building additional tests which require >= Java 17 -->
     <profile>
-      <id>JDK17</id>
+      <id>JDK17-test</id>
       <activation>
         <jdk>[17,)</jdk>
       </activation>
@@ -363,14 +364,19 @@
         <excludeTestCompilation />
       </properties>
     </profile>
-    <!-- For JDK 25+ skip tests which rely on ProGuard because it does not support JDK 25 yet -->
-    <!-- TODO: Remove this once ProGuard supports JDK 25, and there is a solution for https://github.com/Guardsquare/proguard/issues/473 -->
+
+    <!-- For JDK 25+ without jmod files, skip tests which rely on ProGuard because it requires jmod files -->
+    <!-- TODO: Remove this once https://github.com/Guardsquare/proguard/issues/473 is resolved -->
     <profile>
-      <id>JDK25</id>
+      <id>JDK25-proguard</id>
       <activation>
         <jdk>[25,)</jdk>
+        <file>
+          <missing>${java.home}/jmods/java.base.jmod</missing>
+        </file>
       </activation>
       <properties>
+        <!-- Exclude ProGuard-dependent test class -->
         <excludeTestCompilation>com/google/gson/functional/EnumWithObfuscatedTest.java</excludeTestCompilation>
       </properties>
       <build>
diff --git a/pom.xml b/pom.xml
index 8e40596ffb..a983d5ce4f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -120,7 +120,7 @@
                   <!-- Also disallow too new JDK versions; they might introduce new lints, drop support
                     for older compiler Java target versions or cause issues for some Maven plugins.
                     Failing fast for such versions is better than failing with a confusing error during build. -->
-                  <version>[17,22)</version>
+                  <version>[17,26)</version>
                 </requireJavaVersion>
               </rules>
             </configuration>
@@ -561,6 +561,7 @@
         </plugins>
       </build>
     </profile>
+
     <!-- Disable Error Prone before Java 21 -->
     <profile>
       <id>disable-error-prone</id>
diff --git a/test-graal-native-image/pom.xml b/test-graal-native-image/pom.xml
index 0a3b679612..7271f9ec1d 100644
--- a/test-graal-native-image/pom.xml
+++ b/test-graal-native-image/pom.xml
@@ -116,8 +116,9 @@
   </build>
 
   <profiles>
+    <!-- Profile for building additional tests which require >= Java 17 -->
     <profile>
-      <id>JDK17</id>
+      <id>JDK17-test</id>
       <activation>
         <jdk>[17,)</jdk>
       </activation>
diff --git a/test-shrinker/pom.xml b/test-shrinker/pom.xml
index 611179162c..f6bdca175c 100644
--- a/test-shrinker/pom.xml
+++ b/test-shrinker/pom.xml
@@ -210,4 +210,37 @@
       </plugin>
     </plugins>
   </build>
+
+  <profiles>
+    <!-- For JDK 25+ without jmod files, skip tests which rely on ProGuard because it requires jmod files -->
+    <!-- TODO: Remove this once https://github.com/Guardsquare/proguard/issues/473 is resolved -->
+    <profile>
+      <id>JDK25-proguard</id>
+      <activation>
+        <jdk>[25,)</jdk>
+        <file>
+          <missing>${java.home}/jmods/java.base.jmod</missing>
+        </file>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>com.github.wvengen</groupId>
+            <artifactId>proguard-maven-plugin</artifactId>
+            <configuration>
+              <skip>true</skip>
+            </configuration>
+          </plugin>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-failsafe-plugin</artifactId>
+            <configuration>
+              <!-- Skip tests because they cannot succeed if ProGuard did not run -->
+              <skipITs>true</skipITs>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+  </profiles>
 </project>