diff --git a/src/processor/memory/rom/mbcs.rs b/src/processor/memory/rom/mbcs.rs
index 2b22087..f867123 100644
--- a/src/processor/memory/rom/mbcs.rs
+++ b/src/processor/memory/rom/mbcs.rs
@@ -143,12 +143,10 @@ impl Mbc for Mbc1 {
             }
             0x6000..0x8000 => {
                 // mode select
-                self.bank_mode = if data == 0x1 {
+                self.bank_mode = if (data & 0x1) == 0x1 {
                     BankingMode::Advanced
-                } else if data == 0x0 {
-                    BankingMode::Simple
                 } else {
-                    self.bank_mode
+                    BankingMode::Simple
                 };
             }
             _ => {}