--- a/src/th06/ecl.rs
+++ b/src/th06/ecl.rs
@@ -271,7 +271,7 @@ declare_sub_instructions!{
     82 => fn SetExtendedBulletAttributes(a: i32, b: i32, c: i32, d: i32, e: f32, f: f32, g: f32, h: f32),
     83 => fn ChangeBulletsInStarBonus(),
     // TODO: Found in stage 4 onward.
-    84 => fn UNK_ins84(param: i32),
+    84 => fn SetBulletSound(sound: i32),
     85 => fn NewLaser(laser_type: i16, sprite_idx_offset: i16, angle: f32, speed: f32, start_offset: f32, end_offset: f32, max_length: f32, width: f32, start_duration: i32, duration: i32, end_duration: i32, grazing_delay: i32, grazing_extra_duration: i32, UNK1: i32),
     86 => fn NewLaserTowardsPlayer(laser_type: i16, sprite_idx_offset: i16, angle: f32, speed: f32, start_offset: f32, end_offset: f32, max_length: f32, width: f32, start_duration: i32, duration: i32, end_duration: i32, grazing_delay: i32, grazing_extra_duration: i32, UNK1: i32),
     87 => fn SetUpcomingLaserId(id: u32),