diff --git a/include/mbedtls/ripemd160.h b/include/mbedtls/ripemd160.h
index 0c8e568..c74b7d2 100644
--- a/include/mbedtls/ripemd160.h
+++ b/include/mbedtls/ripemd160.h
@@ -33,6 +33,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+/* MBEDTLS_ERR_RIPEMD160_HW_ACCEL_FAILED is deprecated and should not be used.
+ */
 #define MBEDTLS_ERR_RIPEMD160_HW_ACCEL_FAILED             -0x0031  /**< RIPEMD160 hardware accelerator failed */
 
 #ifdef __cplusplus