diff --git a/crypto/ec/ec_lcl.h b/crypto/ec/ec_lcl.h
index e3b1c5d525ee1356ba708662b77c84d0d65995f7..742e90a13b262f26871792107d77dc11ec078164 100644
--- a/crypto/ec/ec_lcl.h
+++ b/crypto/ec/ec_lcl.h
@@ -297,6 +297,12 @@ struct ec_key_st {
     EC_GROUP *group;
     EC_POINT *pub_key;
     BIGNUM *priv_key;
+    /*
+     * Arbitrary extra data.
+     * For example in X25519 this contains the raw private key in a 32 byte
+     * buffer.
+     */
+    void *custom_data;
     unsigned int enc_flag;
     point_conversion_form_t conv_form;
     int references;
@@ -316,6 +322,11 @@ struct ec_point_st {
                                  * Z) represents (X/Z^2, Y/Z^3) if Z != 0 */
     int Z_is_one;               /* enable optimized point arithmetics for
                                  * special case */
+    /*
+     * Arbitrary extra data.
+     * For example in X25519 this contains the public key in a 32 byte buffer.
+     */
+    void *custom_data;
 } /* EC_POINT */ ;
 
 NISTP224_PRE_COMP *EC_nistp224_pre_comp_dup(NISTP224_PRE_COMP *);