diff --git a/src/oam.s b/src/oam.s
index 34f8d39..b9280a6 100644
--- a/src/oam.s
+++ b/src/oam.s
@@ -23,6 +23,8 @@ OAM_Init::
 
     ret
 
+; Wait for DMA transfer from $XX00 to complete (~160 cycles)
+; @param a $XX
 waitForDMA:
     ld [rDMA], a
     ld a, 40