diff --git a/src/kernel/ps/ProcessHandle.hx b/src/kernel/ps/ProcessHandle.hx
index fa21511..3a1e320 100644
--- a/src/kernel/ps/ProcessHandle.hx
+++ b/src/kernel/ps/ProcessHandle.hx
@@ -49,7 +49,9 @@ class ProcessHandle {
 	}
 
 	public function write(message: String): Void {
-		this.config.onWrite.invoke(message);
+		if (this.config.onWrite != null){
+			this.config.onWrite.invoke(message);
+		}
 	}
 
 	public function writeLine(message: String): Void {