diff --git a/Machines/Atari2600/Atari2600.cpp b/Machines/Atari2600/Atari2600.cpp
index 25a8b9792..50745cb9b 100644
--- a/Machines/Atari2600/Atari2600.cpp
+++ b/Machines/Atari2600/Atari2600.cpp
@@ -121,6 +121,7 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 					case 0x0a:
 					case 0x0b:
 						// TODO: pot ports
+						returnValue &= 0;
 					break;
 
 					case 0x0c: