diff --git a/firmware/hackrf_usb/sgpio_m0.s b/firmware/hackrf_usb/sgpio_m0.s
index f77b81da..2bc1505b 100644
--- a/firmware/hackrf_usb/sgpio_m0.s
+++ b/firmware/hackrf_usb/sgpio_m0.s
@@ -168,7 +168,7 @@ loop:
 	// Grab the exchange interrupt staus...
 	ldr r0, [sgpio_int, #INT_STATUS]                                                        // 10, twice
 
-	// ... check to see if it has any interrupt bits set...
+	// ... check to see if bit #0 (slice A) was set, by shifting it into the carry bit...
 	lsr r0, #1                                                                              // 1, twice
 
 	// ... and if not, jump back to the beginning.