diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 2526273fb..803d08efd 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -1150,7 +1150,6 @@ int mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
 /**
  * \brief           This function exports an elliptic curve private key.
  *
- * \param grp_id    The ECP group identifier.
  * \param key       The private key.
  * \param buf       The output buffer for containing the binary representation
  *                  of the key. (Big endian integer for Weierstrass curves, byte
@@ -1164,7 +1163,7 @@ int mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
  *                  the group is not implemented.
  * \return          Another negative error code on different kinds of failure.
  */
-int mbedtls_ecp_write_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
+int mbedtls_ecp_write_key( mbedtls_ecp_keypair *key,
                            unsigned char *buf, size_t buflen );
 
 /**
diff --git a/library/ecp.c b/library/ecp.c
index 94c796049..63e08dfc1 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2999,23 +2999,18 @@ cleanup:
 /*
  * Write a private key.
  */
-int mbedtls_ecp_write_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
+int mbedtls_ecp_write_key( mbedtls_ecp_keypair *key,
                            unsigned char *buf, size_t buflen )
 {
-    int ret = 0;
+    int ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
 
-    ECP_VALIDATE_RET( key  != NULL );
-    ECP_VALIDATE_RET( buf  != NULL );
-
-    if( ( ret = mbedtls_ecp_group_load( &key->grp, grp_id ) ) != 0 )
-        return( ret );
-
-    ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
+    ECP_VALIDATE_RET( key != NULL );
+    ECP_VALIDATE_RET( buf != NULL );
 
 #if defined(ECP_MONTGOMERY)
     if( mbedtls_ecp_get_type( &key->grp ) == MBEDTLS_ECP_TYPE_MONTGOMERY )
     {
-        if( grp_id == MBEDTLS_ECP_DP_CURVE25519 )
+        if( key->grp.id == MBEDTLS_ECP_DP_CURVE25519 )
         {
             if( buflen < ECP_CURVE25519_KEY_SIZE )
                 return MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL;
diff --git a/library/pkwrite.c b/library/pkwrite.c
index 4288cd769..ca5562a77 100644
--- a/library/pkwrite.c
+++ b/library/pkwrite.c
@@ -168,7 +168,7 @@ static int pk_write_ec_private( unsigned char **p, unsigned char *start,
     size_t byte_length = ( ec->grp.pbits + 7 ) / 8;
     unsigned char tmp[MBEDTLS_ECP_MAX_BYTES];
 
-    ret = mbedtls_ecp_write_key( ec->grp.id, ec, tmp, byte_length );
+    ret = mbedtls_ecp_write_key( ec, tmp, byte_length );
     if( ret != 0 )
         goto exit;
     ret = mbedtls_asn1_write_octet_string( p, start, tmp, byte_length );
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index a620d3085..b3da8f789 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1326,8 +1326,8 @@ static psa_status_t psa_internal_export_key( const psa_key_slot_t *slot,
         if( bytes > data_size )
             return( PSA_ERROR_BUFFER_TOO_SMALL );
         status = mbedtls_to_psa_error(
-            mbedtls_ecp_write_key(slot->data.ecp->grp.id, slot->data.ecp,
-                                  data, bytes) );
+            mbedtls_ecp_write_key( slot->data.ecp,
+                                   data, bytes ) );
         if( status != PSA_SUCCESS )
             return( status );
         memset( data + bytes, 0, data_size - bytes );
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index d014e8a7d..ec31c11a1 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -1090,7 +1090,7 @@ void mbedtls_ecp_read_key( int grp_id, data_t* in_key, int expected, int canonic
         {
             unsigned char buf[MBEDTLS_ECP_MAX_BYTES];
 
-            ret = mbedtls_ecp_write_key( grp_id, &key, buf, in_key->len );
+            ret = mbedtls_ecp_write_key( &key, buf, in_key->len );
             TEST_ASSERT( ret == 0 );
 
             ASSERT_COMPARE( in_key->x, in_key->len,
@@ -1101,13 +1101,13 @@ void mbedtls_ecp_read_key( int grp_id, data_t* in_key, int expected, int canonic
             unsigned char export1[MBEDTLS_ECP_MAX_BYTES];
             unsigned char export2[MBEDTLS_ECP_MAX_BYTES];
 
-            ret = mbedtls_ecp_write_key( grp_id, &key, export1, in_key->len );
+            ret = mbedtls_ecp_write_key( &key, export1, in_key->len );
             TEST_ASSERT( ret == 0 );
 
             ret = mbedtls_ecp_read_key( grp_id, &key2, export1, in_key->len );
             TEST_ASSERT( ret == expected );
 
-            ret = mbedtls_ecp_write_key( grp_id, &key2, export2, in_key->len );
+            ret = mbedtls_ecp_write_key( &key2, export2, in_key->len );
             TEST_ASSERT( ret == 0 );
 
             ASSERT_COMPARE( export1, in_key->len,