diff --git a/src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/FormatTask.kt b/src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/FormatTask.kt
index 6b102b04..8182662d 100644
--- a/src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/FormatTask.kt
+++ b/src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/FormatTask.kt
@@ -34,6 +34,7 @@ open class FormatTask @Inject constructor(
             spec.classpath.setFrom(ktlintClasspath, ruleSetsClasspath)
             spec.forkOptions { options ->
                 options.maxHeapSize = workerMaxHeapSize.get()
+                options.jvmArgs = listOf("--add-opens=java.base/java.lang=ALL-UNNAMED") // https://github.com/gradle/gradle/issues/21013
             }
         }