diff --git a/src/mem.rs b/src/mem.rs
index d0999b0..33596f7 100644
--- a/src/mem.rs
+++ b/src/mem.rs
@@ -187,6 +187,7 @@ impl MemoryMapper for SegaGGMapper {
 }
 
 #[derive(PartialEq, Eq, Clone, Debug)]
+#[allow(dead_code)]
 enum Dest {
     Rom { start: u32 },
     Ram { start: u16 },
diff --git a/src/system.rs b/src/system.rs
index 2e4619c..257d331 100644
--- a/src/system.rs
+++ b/src/system.rs
@@ -50,6 +50,8 @@ impl io::Device for System {
                 Ok(())
             }
             _ => Ok(()),
+            #[allow(unreachable_patterns)]
+            /* This is only for debugging missing devices */
             _ => Err(format!(
                 "unknown system port output write address @{:04X} {:02X}",
                 addr, val
@@ -61,6 +63,8 @@ impl io::Device for System {
         match addr & 0xFF {
             0x0 => Ok((!(*self.start_button.borrow() as u8) << 7) | u8::from(&self.region)),
             _ => Ok(0),
+            #[allow(unreachable_patterns)]
+            /* This is only for debugging missing devices */
             _ => Err(format!("unknown system port input address @{:04X}", addr)),
         }
     }