diff --git a/stream/mts/psi/crc.go b/stream/mts/psi/crc.go
index 55bad3ed..c173d63c 100644
--- a/stream/mts/psi/crc.go
+++ b/stream/mts/psi/crc.go
@@ -38,7 +38,7 @@ func addCrc(out []byte) []byte {
 	return out
 }
 
-// updateCrc updates the crc of psi bytes slice that may have been modified
+// updateCrc updates the crc of bytes slice, writing the checksum into the last four bytes.
 func updateCrc(out []byte) []byte {
 	crc32 := crc32_Update(0xffffffff, crc32_MakeTable(bits.Reverse32(crc32.IEEE)), out[1:len(out)-4])
 	out[len(out)-4] = byte(crc32 >> 24)