diff --git a/README.md b/README.md
index f755651d..8c9e6fb7 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,6 @@
 <img src="https://raw.githubusercontent.com/eclipse-zenoh/zenoh/master/zenoh-dragon.png" height="150">
 
+[![CI](https://github.com/eclipse-zenoh/zenoh-kotlin/workflows/CI/badge.svg)](https://github.com/eclipse-zenoh/zenoh-kotlin/actions?query=workflow%3A%22CI%22)
 [![Discussion](https://img.shields.io/badge/discussion-on%20github-blue)](https://github.com/eclipse-zenoh/roadmap/discussions)
 [![Discord](https://img.shields.io/badge/chat-on%20discord-blue)](https://discord.gg/2GJ958VuHs)
 [![License](https://img.shields.io/badge/License-EPL%202.0-blue)](https://choosealicense.com/licenses/epl-2.0/)
diff --git a/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIGetCallback.kt b/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIGetCallback.kt
index 695d24ce..5adb1653 100644
--- a/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIGetCallback.kt
+++ b/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIGetCallback.kt
@@ -14,7 +14,7 @@
 
 package io.zenoh.jni.callbacks
 
-fun interface JNIGetCallback {
+internal fun interface JNIGetCallback {
 
     fun run(
         replierId: String,
diff --git a/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIQueryableCallback.kt b/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIQueryableCallback.kt
index de04800e..402d1cf4 100644
--- a/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIQueryableCallback.kt
+++ b/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNIQueryableCallback.kt
@@ -14,7 +14,7 @@
 
 package io.zenoh.jni.callbacks
 
-fun interface JNIQueryableCallback {
+internal fun interface JNIQueryableCallback {
     fun run(keyExprPtr: Long,
             selectorParams: String,
             withValue: Boolean,
diff --git a/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNISubscriberCallback.kt b/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNISubscriberCallback.kt
index cc400f73..fc0a4ca5 100644
--- a/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNISubscriberCallback.kt
+++ b/zenoh-kotlin/src/main/kotlin/io/zenoh/jni/callbacks/JNISubscriberCallback.kt
@@ -14,7 +14,7 @@
 
 package io.zenoh.jni.callbacks
 
-fun interface JNISubscriberCallback {
+internal fun interface JNISubscriberCallback {
     fun run(
         keyExpr: Long,
         payload: ByteArray,