diff --git a/library/ecp.c b/library/ecp.c
index 009be61..74c0232 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2666,14 +2666,17 @@
 
     if( mbedtls_mpi_cmp_int( m, 0 ) == 0 )
     {
+        MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, P ) );
         MBEDTLS_MPI_CHK( mbedtls_ecp_set_zero( R ) );
     }
     else if( mbedtls_mpi_cmp_int( m, 1 ) == 0 )
     {
+        MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, P ) );
         MBEDTLS_MPI_CHK( mbedtls_ecp_copy( R, P ) );
     }
     else if( mbedtls_mpi_cmp_int( m, -1 ) == 0 )
     {
+        MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, P ) );
         MBEDTLS_MPI_CHK( mbedtls_ecp_copy( R, P ) );
         MPI_ECP_NEG( &R->Y );
     }