diff --git a/include/mbedtls/sha1.h b/include/mbedtls/sha1.h
index bcaeab5..96da3fe 100644
--- a/include/mbedtls/sha1.h
+++ b/include/mbedtls/sha1.h
@@ -42,6 +42,7 @@
 
 /* MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED is deprecated and should not be used. */
 #define MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED                  -0x0035  /**< SHA-1 hardware accelerator failed */
+#define MBEDTLS_ERR_SHA1_BAD_INPUT_DATA                   -0x0073  /**< Invalid input data. */
 
 #ifdef __cplusplus
 extern "C" {