diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 82f28b8..4671e75 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -694,6 +694,13 @@
                             G ## _n,  sizeof( G ## _n  ) )
 
 #if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
+/* Constants used by ecp_use_curve25519() */
+static const unsigned char curve25519_a24[] = { 0x01, 0xDB, 0x42 };
+static const unsigned char curve25519_part_of_n[] = {
+    0x14, 0xDE, 0xF9, 0xDE, 0xA2, 0xF7, 0x9C, 0xD6,
+    0x58, 0x12, 0x63, 0x1A, 0x5C, 0xF5, 0xD3, 0xED,
+};
+
 /*
  * Specialized function for creating the Curve25519 group
  */
@@ -702,7 +709,8 @@
     int ret;
 
     /* Actually ( A + 2 ) / 4 */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &grp->A, 16, "01DB42" ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &grp->A,
+                        curve25519_a24, sizeof( curve25519_a24 ) ) );
 
     /* P = 2^255 - 19 */
     MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &grp->P, 1 ) );
@@ -711,8 +719,8 @@
     grp->pbits = mbedtls_mpi_bitlen( &grp->P );
 
     /* N = 2^252 + 27742317777372353535851937790883648493 */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &grp->N, 16,
-                                              "14DEF9DEA2F79CD65812631A5CF5D3ED" ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &grp->N,
+                     curve25519_part_of_n, sizeof( curve25519_part_of_n ) ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &grp->N, 252, 1 ) );
 
     /* Y intentionally not set, since we use x/z coordinates.
@@ -755,6 +763,15 @@
 #endif /* MBEDTLS_ECP_DP_CURVE25519_ENABLED */
 
 #if defined(MBEDTLS_ECP_DP_CURVE448_ENABLED)
+/* Constants used by ecp_use_curve448() */
+static const unsigned char curve448_a24[] = { 0x98, 0xAA };
+static const unsigned char curve448_part_of_n[] = {
+    0x83, 0x35, 0xDC, 0x16, 0x3B, 0xB1, 0x24,
+    0xB6, 0x51, 0x29, 0xC9, 0x6F, 0xDE, 0x93,
+    0x3D, 0x8D, 0x72, 0x3A, 0x70, 0xAA, 0xDC,
+    0x87, 0x3D, 0x6D, 0x54, 0xA7, 0xBB, 0x0D,
+};
+
 /*
  * Specialized function for creating the Curve448 group
  */
@@ -766,7 +783,8 @@
     mbedtls_mpi_init( &Ns );
 
     /* Actually ( A + 2 ) / 4 */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &grp->A, 16, "98AA" ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &grp->A,
+                        curve448_a24, sizeof( curve448_a24 ) ) );
 
     /* P = 2^448 - 2^224 - 1 */
     MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &grp->P, 1 ) );
@@ -784,8 +802,8 @@
 
     /* N = 2^446 - 13818066809895115352007386748515426880336692474882178609894547503885 */
     MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &grp->N, 446, 1 ) );
-    MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &Ns, 16,
-                                              "8335DC163BB124B65129C96FDE933D8D723A70AADC873D6D54A7BB0D" ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &Ns,
+                        curve448_part_of_n, sizeof( curve448_part_of_n ) ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &grp->N, &grp->N, &Ns ) );
 
     /* Actually, the required msb for private keys */