diff --git a/c64/kernal/iec_assert_atn.s b/c64/kernal/iec_assert_atn.s
index 407ee358..57560c3a 100644
--- a/c64/kernal/iec_assert_atn.s
+++ b/c64/kernal/iec_assert_atn.s
@@ -1,5 +1,5 @@
 iec_assert_atn:
-	lda $dd0d
+	lda $dd00
 	ora #$08
-	sta $dd0d
+	sta $dd00
 	rts