diff --git a/library/ecp.c b/library/ecp.c
index cc79b77..68f20f7 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -589,7 +589,7 @@
 /*
  * Set a group from an ECParameters record (RFC 4492)
  */
-int ecp_tls_read_group( ecp_group *grp, const unsigned char *buf, size_t len )
+int ecp_tls_read_group( ecp_group *grp, const unsigned char **buf, size_t len )
 {
     ecp_group_id id;
 
@@ -602,13 +602,15 @@
     /*
      * First byte is curve_type; only named_curve is handled
      */
-    if( *buf++ != POLARSSL_ECP_TLS_NAMED_CURVE )
+    if( *(*buf)++ != POLARSSL_ECP_TLS_NAMED_CURVE )
         return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
 
     /*
      * Next two bytes are the namedcurve value
      */
-    id = 256 * buf[0] + buf[1];
+    id = *(*buf)++;
+    id <<= 8;
+    id |= *(*buf)++;
     return ecp_use_known_dp( grp, id );
 }