diff --git a/fpt/src/memory/lib.rs b/fpt/src/memory/lib.rs
index 48e2512..7de0e20 100644
--- a/fpt/src/memory/lib.rs
+++ b/fpt/src/memory/lib.rs
@@ -9,11 +9,10 @@ use crate::memory::{create_empty_mbc, create_mbc, Cartridge};
 pub type Address = usize;
 pub type MemoryRange = Range<Address>;
 
-#[derive(Clone)]
 pub struct Memory {
     mem: Vec<u8>,
     pub bootrom_loaded: bool,
-    pub cartridge: Rc<RefCell<dyn Cartridge>>,
+    pub cartridge: Box<RefCell<dyn Cartridge>>,
     bootrom: &'static [u8; 256],
     code_listing: Vec<Option<String>>,
     pub buttons: Buttons,
diff --git a/fpt/src/memory/mbc_builder.rs b/fpt/src/memory/mbc_builder.rs
index 333c529..2cc4002 100644
--- a/fpt/src/memory/mbc_builder.rs
+++ b/fpt/src/memory/mbc_builder.rs
@@ -1,18 +1,17 @@
 use std::cell::RefCell;
-use std::rc::Rc;
 
 use super::cartridge::{get_cartridge_type, EmptyCartridge};
 use super::mbc_none::NoMbcCartridge;
 use super::Cartridge;
 
-pub fn create_mbc(cartridge_data: &[u8]) -> Option<Rc<RefCell<dyn Cartridge>>> {
+pub fn create_mbc(cartridge_data: &[u8]) -> Option<Box<RefCell<dyn Cartridge>>> {
     // https://gbdev.io/pandocs/The_Cartridge_Header.html#0147--cartridge-type
     match get_cartridge_type(cartridge_data) {
-        0x00 => Some(Rc::new(RefCell::new(NoMbcCartridge::new(cartridge_data)))), // rom only
+        0x00 => Some(Box::new(RefCell::new(NoMbcCartridge::new(cartridge_data)))), // rom only
         _ => None,
     }
 }
 
-pub fn create_empty_mbc() -> Rc<RefCell<dyn Cartridge>> {
-    Rc::new(RefCell::new(EmptyCartridge::new()))
+pub fn create_empty_mbc() -> Box<RefCell<dyn Cartridge>> {
+    Box::new(RefCell::new(EmptyCartridge::new()))
 }
diff --git a/fpt/src/memory/mbc_none.rs b/fpt/src/memory/mbc_none.rs
index a85be87..59ef845 100644
--- a/fpt/src/memory/mbc_none.rs
+++ b/fpt/src/memory/mbc_none.rs
@@ -5,7 +5,7 @@ use super::{map, Address};
 ///
 /// <https://gbdev.io/pandocs/nombc.html>
 pub struct NoMbcCartridge {
-    memory: Vec<u8>,
+    memory: [u8; 0x8000],
 }
 
 impl NoMbcCartridge {
@@ -15,7 +15,7 @@ impl NoMbcCartridge {
             "Expected cartridge size of 0x8000"
         );
         NoMbcCartridge {
-            memory: cartridge.to_vec(),
+            memory: cartridge.try_into().unwrap(),
         }
     }
 }