diff --git a/library/arc4.c b/library/arc4.c
index eeebbdc..e936fc5 100644
--- a/library/arc4.c
+++ b/library/arc4.c
@@ -169,7 +169,7 @@
         if( verbose != 0 )
             mbedtls_printf( "  ARC4 test #%d: ", i + 1 );
 
-        memcpy( ibuf, arc4_test_pt[i], 8 );
+        mbedtls_platform_memcpy( ibuf, arc4_test_pt[i], 8 );
 
         mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );
         mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );