diff --git a/orx-jvm/orx-kotlin-parser/build.gradle b/orx-jvm/orx-kotlin-parser/build.gradle
deleted file mode 100644
index f6808a02..00000000
--- a/orx-jvm/orx-kotlin-parser/build.gradle
+++ /dev/null
@@ -1,26 +0,0 @@
-plugins {
-    id("org.openrndr.extra.convention.kotlin-jvm")
-    id("antlr")
-}
-
-sourceSets {
-    main {
-        java {
-            srcDir("build/generated-src/antlr")
-        }
-    }
-}
-
-generateGrammarSource {
-    maxHeapSize = "64m"
-    arguments += ["-visitor", "-long-messages"]
-    outputDirectory = file("${project.buildDir}/generated-src/antlr/org/openrndr/extra/kotlin/antlr".toString())
-}
-
-dependencies {
-    antlr(libs.antlr.core)
-    implementation(libs.antlr.runtime)
-}
-
-tasks.getByName("compileKotlin").dependsOn("generateGrammarSource")
-tasks.getByName("sourcesJar").dependsOn("generateGrammarSource")
\ No newline at end of file
diff --git a/orx-jvm/orx-kotlin-parser/build.gradle.kts b/orx-jvm/orx-kotlin-parser/build.gradle.kts
new file mode 100644
index 00000000..ca45f3c6
--- /dev/null
+++ b/orx-jvm/orx-kotlin-parser/build.gradle.kts
@@ -0,0 +1,33 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    org.openrndr.extra.convention.`kotlin-jvm`
+    antlr
+}
+
+tasks.generateGrammarSource {
+    maxHeapSize = "64m"
+    arguments.addAll(listOf("-visitor", "-long-messages", "-package", "org.openrndr.extra.kotlin.antlr"))
+    outputDirectory =  file("${project.buildDir}/generated-src/antlr/org/openrndr/extra/kotlin/antlr".toString())
+}
+
+sourceSets {
+    main {
+        java {
+            srcDir("build/generated-src/antlr")
+        }
+    }
+}
+
+tasks.withType<KotlinCompile> {
+    kotlinOptions.freeCompilerArgs = listOf("-opt-in=kotlin.RequiresOptIn")
+}
+
+dependencies {
+    antlr(libs.antlr.core)
+    implementation(libs.antlr.runtime)
+    testImplementation(libs.kluent)
+}
+
+tasks.getByName("compileKotlin").dependsOn("generateGrammarSource")
+tasks.getByName("sourcesJar").dependsOn("generateGrammarSource")
diff --git a/orx-jvm/orx-kotlin-parser/src/main/antlr/KotlinParser.g4 b/orx-jvm/orx-kotlin-parser/src/main/antlr/KotlinParser.g4
index 6a15689c..53356a1f 100644
--- a/orx-jvm/orx-kotlin-parser/src/main/antlr/KotlinParser.g4
+++ b/orx-jvm/orx-kotlin-parser/src/main/antlr/KotlinParser.g4
@@ -4,11 +4,6 @@
 
 parser grammar KotlinParser;
 
-@header {
-package org.openrndr.extra.kotlin.antlr;
-}
-
-
 options { tokenVocab = KotlinLexer; }
 
 // SECTION: general
diff --git a/orx-jvm/orx-kotlin-parser/src/main/antlr/UnicodeClasses.g4 b/orx-jvm/orx-kotlin-parser/src/main/antlr/UnicodeClasses.g4
index e11ccb9b..53728480 100644
--- a/orx-jvm/orx-kotlin-parser/src/main/antlr/UnicodeClasses.g4
+++ b/orx-jvm/orx-kotlin-parser/src/main/antlr/UnicodeClasses.g4
@@ -6,11 +6,6 @@
 
 lexer grammar UnicodeClasses;
 
-@header {
-package org.openrndr.extra.kotlin.antlr;
-}
-
-
 UNICODE_CLASS_LL:
 	'\u0061'..'\u007A' |
 	'\u00B5' |