diff --git a/ubb-la/ubb-la.c b/ubb-la/ubb-la.c
index c63a023..2dd147d 100644
--- a/ubb-la/ubb-la.c
+++ b/ubb-la/ubb-la.c
@@ -29,6 +29,13 @@
 
 #define	KEY_MASK	0x5fc0000
 
+/*
+ * The initial skip is for samples loaded into the FIFO when starting the
+ * command, before waiting for the trigger. A completely filled FIFO would
+ * hold 16 * 32 bits or 128 samples. In reality, we observe 122 samples for
+ * sample rates up to 24 MHz and 123 samples for 42 or 56 MHz.
+ */
+
 #define	INITIAL_SKIP	122	/* should be 123 for higher speeds */