diff --git a/library/pk.c b/library/pk.c
index 9f7ab4b..29123eb 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -512,7 +512,7 @@
 
     padding_len = to_len - unpadded_len;
     memset( to, 0x00, padding_len );
-    memcpy( to + padding_len, *from, unpadded_len );
+    mbedtls_platform_memcpy( to + padding_len, *from, unpadded_len );
     ( *from ) += unpadded_len;
 
     return( 0 );