diff --git a/.github/workflows/gradle.yml b/.github/workflows/gradle.yml
index 2a034776..d5a02c79 100644
--- a/.github/workflows/gradle.yml
+++ b/.github/workflows/gradle.yml
@@ -9,21 +9,30 @@ on:
 jobs:
   gradle:
     strategy:
+      fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
+        # 11 is the baseline the published main artifact targets, 21 the runtime most
+        # consumers are on. Compiling to 11 on a 21 JDK cannot catch a problem that only
+        # appears on an 11 runtime, so both are run.
+        java-version: [11, 21]
     runs-on: ${{ matrix.os }}
     steps:
     - name: Checkout
       uses: actions/checkout@v4
-    - name: Set up JDK 21
+    # Both JDKs are installed, 21 last so it becomes JAVA_HOME and Gradle's daemon runs
+    # there. The matrix JDK is picked up by the toolchain to compile and run the tests.
+    - name: Set up JDK ${{ matrix.java-version }} and 21
       uses: actions/setup-java@v4
       with:
         distribution: 'temurin'
-        java-version: 21
+        java-version: |
+          ${{ matrix.java-version }}
+          21
     - name: Setup Gradle
       uses: gradle/actions/setup-gradle@v3
     - name: Build with Gradle
-      run: ./gradlew build
+      run: ./gradlew build -PjavaTestVersion=${{ matrix.java-version }}
       env:
         GITHUB_USERNAME: ${{ secrets.GITHUB_USERNAME }}
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/build.gradle b/build.gradle
index 38d5ee39..9dec7c54 100644
--- a/build.gradle
+++ b/build.gradle
@@ -33,8 +33,17 @@ plugins {
 }
 
 java {
+    // Bytecode targets 11 to match the Maven main artifact, whatever JDK compiles it.
+    // The published jdk21 classifier is produced by Maven, which is what publishes.
+    sourceCompatibility = 11
+    targetCompatibility = 11
+
+    // -PjavaTestVersion selects the JDK that compiles and runs the tests, so CI can
+    // exercise the same Java 11 bytecode on an 11 and a 21 runtime while Gradle itself
+    // stays on the launcher JDK.
     toolchain {
-        languageVersion = JavaLanguageVersion.of(21)
+        languageVersion = JavaLanguageVersion.of(
+            (project.findProperty('javaTestVersion') ?: '21') as Integer)
     }
     
     withJavadocJar()
@@ -111,6 +120,15 @@ repositories {
         }
     }
 }
+
+// cfparser is tracked as a SNAPSHOT. Gradle treats that as a changing module and caches
+// it for 24 hours, and the CI workflows restore a Gradle cache -- so a green run shortly
+// after a cfparser republish can have tested the *previous* artifact. Re-resolve every
+// time; it is one small jar, and a stale one is worth far more than the download.
+configurations.all {
+    resolutionStrategy.cacheChangingModulesFor 0, 'seconds'
+}
+
 dependencies {
     implementation 'com.github.cfmleditor:cfml.parsing:2.16.1-SNAPSHOT'
     implementation 'commons-cli:commons-cli:1.2'
diff --git a/pom.xml b/pom.xml
index 3d965eb5..cbfe4e01 100644
--- a/pom.xml
+++ b/pom.xml
@@ -77,8 +77,12 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
-		<maven.compiler.source>21</maven.compiler.source>
-		<maven.compiler.target>21</maven.compiler.target>
+		<!-- The main artifact is Java 11 so it loads on every supported runtime; the
+		     jdk21 classifier below is the same source compiled at 21. release rather
+		     than source/target because it checks the API surface, not just the
+		     language level. -->
+		<maven.compiler.release>11</maven.compiler.release>
+		<jdk21.release>21</jdk21.release>
 		<maven.compiler.proc>none</maven.compiler.proc>
 
 		<cfparser.version>2.16.1-SNAPSHOT</cfparser.version>
@@ -210,6 +214,28 @@
 					</execution>
 				</executions>
 			</plugin>
+			<!-- Two artifacts from one source tree, mirroring cfparser. default-compile
+			     emits Java 11 into target/classes for the main jar and the shaded -all
+			     jar; compile-jdk21 emits Java 21 into target/classes-jdk21 for the
+			     jdk21 classifier. -->
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>3.13.0</version>
+				<executions>
+					<execution>
+						<id>compile-jdk21</id>
+						<phase>compile</phase>
+						<goals>
+							<goal>compile</goal>
+						</goals>
+						<configuration>
+							<release>${jdk21.release}</release>
+							<outputDirectory>${project.build.directory}/classes-jdk21</outputDirectory>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-jar-plugin</artifactId>
@@ -229,11 +255,48 @@
 						</manifestEntries>
 					</archive>
 				</configuration>
+				<executions>
+					<execution>
+						<id>jar-jdk21</id>
+						<phase>package</phase>
+						<goals>
+							<goal>jar</goal>
+						</goals>
+						<configuration>
+							<classifier>jdk21</classifier>
+							<classesDirectory>${project.build.directory}/classes-jdk21</classesDirectory>
+						</configuration>
+					</execution>
+				</executions>
 			</plugin>
 			<plugin>
 				<artifactId>maven-resources-plugin</artifactId>
 				<version>2.6</version>
 				<executions>
+					<execution>
+						<id>copy-resources-jdk21</id>
+						<!-- classes-jdk21 holds only .class files, so the classified jar
+						     needs the resources copied in. Kept at process-classes for
+						     the reason cfparser's pom documents: setting outputDirectory
+						     on a compiler execution leaks into what dependents resolve,
+						     and a later phase breaks the test run in a way that reads
+						     like a missing resource. -->
+						<phase>process-classes</phase>
+						<goals>
+							<goal>copy-resources</goal>
+						</goals>
+						<configuration>
+							<outputDirectory>${project.build.directory}/classes-jdk21</outputDirectory>
+							<resources>
+								<resource>
+									<directory>${project.build.outputDirectory}</directory>
+									<excludes>
+										<exclude>**/*.class</exclude>
+									</excludes>
+								</resource>
+							</resources>
+						</configuration>
+					</execution>
 					<execution>
 						<id>copy-resources</id>
 						<!-- here the phase you need -->