diff --git a/library/ecp.c b/library/ecp.c
index 682095b..5927abc 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2969,9 +2969,46 @@
 
 #if defined(ECP_MONTGOMERY)
 #if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
-/* The following constants are defined in ecp_curves.c */
-extern const mbedtls_mpi mbedtls_ecp_x25519_bad_point_1;
-extern const mbedtls_mpi mbedtls_ecp_x25519_bad_point_2;
+/* Duplicated macros from ecp_curves.c */
+#if defined(MBEDTLS_HAVE_INT32)
+#define BYTES_TO_T_UINT_8( a, b, c, d, e, f, g, h ) \
+    BYTES_TO_T_UINT_4( a, b, c, d ),                \
+    BYTES_TO_T_UINT_4( e, f, g, h )
+#else /* 64-bits */
+#define BYTES_TO_T_UINT_8( a, b, c, d, e, f, g, h ) \
+    ( (mbedtls_mpi_uint) (a) <<  0 ) |                        \
+    ( (mbedtls_mpi_uint) (b) <<  8 ) |                        \
+    ( (mbedtls_mpi_uint) (c) << 16 ) |                        \
+    ( (mbedtls_mpi_uint) (d) << 24 ) |                        \
+    ( (mbedtls_mpi_uint) (e) << 32 ) |                        \
+    ( (mbedtls_mpi_uint) (f) << 40 ) |                        \
+    ( (mbedtls_mpi_uint) (g) << 48 ) |                        \
+    ( (mbedtls_mpi_uint) (h) << 56 )
+#endif /* bits in mbedtls_mpi_uint */
+#define ECP_MPI_INIT(s, n, p) {s, (n), (mbedtls_mpi_uint *)(p)}
+#define ECP_MPI_INIT_ARRAY(x)   \
+    ECP_MPI_INIT(1, sizeof(x) / sizeof(mbedtls_mpi_uint), x)
+/*
+ * Constants for the two points other than 0, 1, -1 (mod p) in
+ * https://cr.yp.to/ecdh.html#validate
+ * See ecp_check_pubkey_x25519().
+ */
+static const mbedtls_mpi_uint x25519_bad_point_1[] = {
+    BYTES_TO_T_UINT_8( 0xe0, 0xeb, 0x7a, 0x7c, 0x3b, 0x41, 0xb8, 0xae ),
+    BYTES_TO_T_UINT_8( 0x16, 0x56, 0xe3, 0xfa, 0xf1, 0x9f, 0xc4, 0x6a ),
+    BYTES_TO_T_UINT_8( 0xda, 0x09, 0x8d, 0xeb, 0x9c, 0x32, 0xb1, 0xfd ),
+    BYTES_TO_T_UINT_8( 0x86, 0x62, 0x05, 0x16, 0x5f, 0x49, 0xb8, 0x00 ),
+};
+static const mbedtls_mpi_uint x25519_bad_point_2[] = {
+    BYTES_TO_T_UINT_8( 0x5f, 0x9c, 0x95, 0xbc, 0xa3, 0x50, 0x8c, 0x24 ),
+    BYTES_TO_T_UINT_8( 0xb1, 0xd0, 0xb1, 0x55, 0x9c, 0x83, 0xef, 0x5b ),
+    BYTES_TO_T_UINT_8( 0x04, 0x44, 0x5c, 0xc4, 0x58, 0x1c, 0x8e, 0x86 ),
+    BYTES_TO_T_UINT_8( 0xd8, 0x22, 0x4e, 0xdd, 0xd0, 0x9f, 0x11, 0x57 ),
+};
+static const mbedtls_mpi ecp_x25519_bad_point_1 = ECP_MPI_INIT_ARRAY(
+        x25519_bad_point_1 );
+static const mbedtls_mpi ecp_x25519_bad_point_2 = ECP_MPI_INIT_ARRAY(
+        x25519_bad_point_2 );
 
 /*
  * Check that the input point is not one of the low-order points.
@@ -2997,10 +3034,10 @@
     if( mbedtls_mpi_cmp_int( &XmP, 1 ) <= 0 ) /* takes care of 0 and 1 */
         return( MBEDTLS_ERR_ECP_INVALID_KEY );
 
-    if( mbedtls_mpi_cmp_mpi( &XmP, &mbedtls_ecp_x25519_bad_point_1 ) == 0 )
+    if( mbedtls_mpi_cmp_mpi( &XmP, &ecp_x25519_bad_point_1 ) == 0 )
         return( MBEDTLS_ERR_ECP_INVALID_KEY );
 
-    if( mbedtls_mpi_cmp_mpi( &XmP, &mbedtls_ecp_x25519_bad_point_2 ) == 0 )
+    if( mbedtls_mpi_cmp_mpi( &XmP, &ecp_x25519_bad_point_2 ) == 0 )
         return( MBEDTLS_ERR_ECP_INVALID_KEY );
 
     /* Final check: check if XmP + 1 is P (final because it changes XmP!) */