diff --git a/src/mmu.rs b/src/mmu.rs
index 245e95a6f4215c221bec556b7599f8f3bc45f718..509352dac504e56bcf25e6b77e88e92823c2937d 100644
--- a/src/mmu.rs
+++ b/src/mmu.rs
@@ -180,7 +180,7 @@ impl Mmu {
                     && addr >= 0x0200
                     && addr <= 0x08ff
                 {
-                    return self.boot[(addr - 0x0100) as usize];
+                    return self.boot[addr as usize];
                 }
                 self.rom.read(addr)
             }