diff --git a/src/util/inv_mpu.c b/src/util/inv_mpu.c
index 0410390..b6f25ee 100644
--- a/src/util/inv_mpu.c
+++ b/src/util/inv_mpu.c
@@ -94,6 +94,14 @@ static inline int reg_int_cb(struct int_param_s *int_param)
 
 //static int set_int_enable(unsigned char enable);
 
+// cf. https://github.com/NicHub/mpu9250-esp32
+#ifndef min
+#define min(X,Y) (((X) < (Y)) ? (X) : (Y))
+#endif
+#ifndef max
+#define max(X,Y) (((X) > (Y)) ? (X) : (Y))
+#endif
+
 /* Hardware registers needed by driver. */
 struct gyro_reg_s {
     unsigned char who_am_i;