diff --git a/src/NDSCart.cpp b/src/NDSCart.cpp
index a0bd68c0..96cbaa33 100644
--- a/src/NDSCart.cpp
+++ b/src/NDSCart.cpp
@@ -1118,6 +1118,8 @@ u8 CartRetailIR::SPIWrite(u8 val, u32 pos, bool last)
     case 0x08: // ID
         return 0xAA;
     }
+
+    return 0;
 }