diff --git a/du6/program.c b/du6/program.c
index c9af8a3..8914dd2 100644
--- a/du6/program.c
+++ b/du6/program.c
@@ -82,6 +82,7 @@ void run_knowledge_system(struct tree* node) {
         }
     }
     printf("Koniec\n");
+    return;
 }
 
 int main() {