diff --git a/src/peep/peep.c b/src/peep/peep.c
index 494bd62b29..9643b2566e 100644
--- a/src/peep/peep.c
+++ b/src/peep/peep.c
@@ -1002,6 +1002,11 @@ void peep_check_cant_find_exit(rct_peep* peep){
  * start an action. Returns 1 if the correct destination
  * has not yet been reached. xy_distance is how close the
  * peep is to the target.
+ *
+ * @param x (ax)
+ * @param y (cx)
+ * @param distance (bp)
+ * @param peep (esi)
  */
 int peep_update_action(sint16* x, sint16* y, sint16* xy_distance, rct_peep* peep){
 	RCT2_GLOBAL(0xF1AEF0, uint8) = peep->action_sprite_image_offset;
diff --git a/src/scenario.c b/src/scenario.c
index 725775f508..b33c6f6659 100644
--- a/src/scenario.c
+++ b/src/scenario.c
@@ -688,6 +688,8 @@ static int scenario_create_ducks()
 /**
  *
  *  rct2: 0x006E37D2
+ *
+ * @return eax
  */
 unsigned int scenario_rand()
 {
diff --git a/src/world/sprite.c b/src/world/sprite.c
index e454cff11c..60ce0a7caf 100644
--- a/src/world/sprite.c
+++ b/src/world/sprite.c
@@ -417,9 +417,11 @@ void sprite_misc_update_all()
 /**
  * Moves a sprite to a new location.
  *  rct2: 0x0069E9D3
- * ax: x
- * cx: y
- * dx: z
+ *
+ * @param x (ax)
+ * @param y (cx)
+ * @param z (dx)
+ * @param sprite (esi)
  */
 void sprite_move(sint16 x, sint16 y, sint16 z, rct_sprite* sprite){
 	if (x < 0 || y < 0 || x > 0x1FFF || y > 0x1FFF)