diff --git a/include/mgba/internal/gba/cart/gpio.h b/include/mgba/internal/gba/cart/gpio.h
index 9aebfa11b..28c5fa0ea 100644
--- a/include/mgba/internal/gba/cart/gpio.h
+++ b/include/mgba/internal/gba/cart/gpio.h
@@ -69,8 +69,8 @@ struct GBACartridgeHardware {
 	uint16_t* gpioBase;
 
 	uint8_t writeLatch;
-	uint16_t pinState;
-	uint16_t direction;
+	uint8_t pinState;
+	uint8_t direction;
 
 	struct GBARTC rtc;