diff --git a/library/md2.c b/library/md2.c
index 9510843..fb8acdd 100644
--- a/library/md2.c
+++ b/library/md2.c
@@ -112,6 +112,7 @@
     ctx->left = 0;
 }
 
+#if !defined(POLARSSL_MD2_PROCESS_ALT)
 void md2_process( md2_context *ctx )
 {
     int i, j;
@@ -145,6 +146,7 @@
         t  = ctx->cksum[i];
     }
 }
+#endif /* !POLARSSL_MD2_PROCESS_ALT */
 
 /*
  * MD2 process buffer