diff --git a/src/main/java/com/iexec/core/config/AsyncConfig.java b/src/main/java/com/iexec/core/config/AsyncConfig.java
index de948515d..b3e0bc0f1 100644
--- a/src/main/java/com/iexec/core/config/AsyncConfig.java
+++ b/src/main/java/com/iexec/core/config/AsyncConfig.java
@@ -51,7 +51,7 @@ public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
         return new Handler();
     }
 
-    public static class Handler implements AsyncUncaughtExceptionHandler {
+    private class Handler implements AsyncUncaughtExceptionHandler {
 
         @Override
         public void handleUncaughtException(