diff --git a/src/rom.rs b/src/rom.rs
index 2e86a5d..68b2ddc 100644
--- a/src/rom.rs
+++ b/src/rom.rs
@@ -54,10 +54,10 @@ impl Card for Rom {
             return NullableResult::Null;
         }
         let address = address as u16;
-        if address < 0x4000 {
+        if address < 0x8000 {
             self.data.get(address as usize).copied().into()
         } else {
-            self.ram.get((address - 0x4000) as usize).copied().into()
+            self.ram.get((address - 0x8000) as usize).copied().into()
         }
     }
 
@@ -65,8 +65,8 @@ impl Card for Rom {
         if !self.enabled | ((address >> 16) as u16 != self.start) {
             return NullableResult::Null;
         }
-        let address = (address as u16).checked_sub(0x4000)?;
-        if address > self.data.len() as u16 {
+        let address = (address as u16).checked_sub(0x8000)?;
+        if address > self.ram.len() as u16 {
             return NullableResult::Null;
         }
         self.ram[address as usize] = data;