diff --git a/cores/gameboy/t80/T80.vhd b/cores/gameboy/t80/T80.vhd
index 4fb4f20..0ed5250 100644
--- a/cores/gameboy/t80/T80.vhd
+++ b/cores/gameboy/t80/T80.vhd
@@ -375,7 +375,7 @@ begin
 			MCycles <= "000";
 			DO <= "00000000";
 
-			ACC <= (others => '1');
+			ACC <= (others => '0');
 			if Mode = 3 then
 				F <= "11110000";
 			else