diff --git a/src/main/java/rife/bld/extension/CompileKotlinOperation.java b/src/main/java/rife/bld/extension/CompileKotlinOperation.java
index bb30b85..0d671c0 100644
--- a/src/main/java/rife/bld/extension/CompileKotlinOperation.java
+++ b/src/main/java/rife/bld/extension/CompileKotlinOperation.java
@@ -317,6 +317,7 @@ public class CompileKotlinOperation extends AbstractOperation<CompileKotlinOpera
      *     <li>{@link #compileTestClasspath() compilesTestClassPath}</li>
      *     <li>{@link #mainSourceFiles() mainSourceFiles}</li>
      *     <li>{@link #testSourceFiles() testSourceFile}</li>
+     *     <li>{@link CompileKotlinOptions#jdkRelease jdkRelease}</li>
      * </ul>
      *
      * @param project the project to configure the compile operation from
@@ -328,7 +329,8 @@ public class CompileKotlinOperation extends AbstractOperation<CompileKotlinOpera
                 .compileMainClasspath(project.compileMainClasspath())
                 .compileTestClasspath(project.compileTestClasspath())
                 .mainSourceFiles(getKotlinFileList(new File(project.srcMainDirectory(), "kotlin")))
-                .testSourceFiles(getKotlinFileList(new File(project.srcTestDirectory(), "kotlin")));
+                .testSourceFiles(getKotlinFileList(new File(project.srcTestDirectory(), "kotlin")))
+                .compileOptions(new CompileKotlinOptions().jdkRelease(project.javaRelease()));
     }
 
     /**
diff --git a/src/main/java/rife/bld/extension/dokka/DokkaOperation.java b/src/main/java/rife/bld/extension/dokka/DokkaOperation.java
index e38f1f4..2214654 100644
--- a/src/main/java/rife/bld/extension/dokka/DokkaOperation.java
+++ b/src/main/java/rife/bld/extension/dokka/DokkaOperation.java
@@ -219,14 +219,17 @@ public class DokkaOperation extends AbstractProcessOperation<DokkaOperation> {
     /**
      * Configures the operation from a {@link BaseProject}.
      * <p>
-     * Sets the {@link #sourceSet sourceSet} and {@link #moduleName moduleName} from the project.
+     * Sets the {@link #sourceSet sourceSet}, {@link SourceSet#jdkVersion jdkVersion} and {@link #moduleName moduleName}
+     * from the project.
      *
      * @param project the project to configure the operation from
      */
     @Override
     public DokkaOperation fromProject(BaseProject project) {
         project_ = project;
-        sourceSet_ = new SourceSet().src(new File(project.srcMainDirectory(), "kotlin").getAbsolutePath());
+        sourceSet_ = new SourceSet()
+                .src(new File(project.srcMainDirectory(), "kotlin").getAbsolutePath())
+                .jdkVersion(project.javaRelease());
         moduleName_ = project.name();
         return this;
     }