diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index b275e58..3a24bfc 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -4570,8 +4570,8 @@
      * uint16 with the value N, and the PSK itself.
      */
 
-    *cur++ = BYTE_1( data_length );
-    *cur++ = BYTE_0( data_length );
+    *cur++ = MBEDTLS_BYTE_1( data_length );
+    *cur++ = MBEDTLS_BYTE_0( data_length );
     memset( cur, 0, data_length );
     cur += data_length;
     *cur++ = pms[0];