diff --git a/src/mainboard/lenovo/s230u/ec.h b/src/mainboard/lenovo/s230u/ec.h
index 273f58b..7ef06e2 100644
--- a/src/mainboard/lenovo/s230u/ec.h
+++ b/src/mainboard/lenovo/s230u/ec.h
@@ -5,7 +5,7 @@
 
 void lenovo_s230u_ec_init(void);
 
-#define ECMM(x) (*((volatile u8 *)(CONFIG_EC_BASE_ADDRESS + x)))
+#define ECMM(x) (*((volatile u8 *)(uintptr_t)(CONFIG_EC_BASE_ADDRESS + x)))
 #define ec_mm_read(addr) (ECMM(0x100 + addr))
 #define ec_mm_write(addr, data) (ECMM(0x100 + addr) = data)
 #define ec_mm_set_bit(addr, bit) (ECMM(0x100 + addr) |= 1 << bit)