diff --git a/include/mbedtls/poly1305.h b/include/mbedtls/poly1305.h
index 021a3a0..babbc15 100644
--- a/include/mbedtls/poly1305.h
+++ b/include/mbedtls/poly1305.h
@@ -44,6 +44,7 @@
 
 #define MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA         -0x0057 /**< Invalid input parameter(s). */
 #define MBEDTLS_ERR_POLY1305_FEATURE_UNAVAILABLE    -0x0059 /**< Feature not available. For example, s part of the API is not implemented. */
+#define MBEDTLS_ERR_POLY1305_HW_ACCEL_FAILED        -0x005B  /**< Poly1305 hardware accelerator failed. */
 
 #ifdef __cplusplus
 extern "C" {