diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h
index b35b0d1..61d6a1d 100644
--- a/include/polarssl/ecp.h
+++ b/include/polarssl/ecp.h
@@ -376,8 +376,10 @@
  * \param ilen      Actual length of input
  *
  * \return          0 if successful,
- *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid
- *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
+ *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid,
+ *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed,
+ *                  POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE if the point format
+ *                  is not implemented.
  *
  * \note            This function does NOT check that the point actually
  *                  belongs to the given group, see ecp_check_pubkey() for