diff --git a/src/planner.h b/src/planner.h
index 9c8ac01..75932a4 100644
--- a/src/planner.h
+++ b/src/planner.h
@@ -26,6 +26,9 @@ typedef struct Task {
  */
 Task *newTask(char *n, time_t c, time_t d, int p, uint64_t sp);
 
+/*
+ * compare function for Task
+ */
 int cmpTask(Task *a, Task *b);
 
 /*
@@ -47,6 +50,9 @@ typedef struct Event {
  * returns NULL on failure
  */
 Event *newEvent(Task *t, time_t s, time_t e, uint64_t sp);
+/*
+ * compare function for Event
+ */
 int cmpEvent(Event *a, Event *b);
 
 int genPlan(Task *head);