diff --git a/p/prolog.pro b/p/prolog.pro
index 5dfa88e5..473a6b14 100644
--- a/p/prolog.pro
+++ b/p/prolog.pro
@@ -1 +1,4 @@
-write('Hello World').
+helloWorld :-
+  write('Hello World').
+
+:- helloWorld.