diff --git a/library/sha256.c b/library/sha256.c
index 1c200c8..3ecacc0 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -280,7 +280,7 @@
 
     if( left && ilen >= fill )
     {
-        memcpy( (void *) (ctx->buffer + left), input, fill );
+        mbedtls_platform_memcpy( (void *) (ctx->buffer + left), input, fill );
 
         if( ( ret = mbedtls_internal_sha256_process( ctx, ctx->buffer ) ) != 0 )
             return( ret );
@@ -300,7 +300,7 @@
     }
 
     if( ilen > 0 )
-        memcpy( (void *) (ctx->buffer + left), input, ilen );
+        mbedtls_platform_memcpy( (void *) (ctx->buffer + left), input, ilen );
 
     return( 0 );
 }