--- a/samplicate.c
+++ b/samplicate.c
@@ -560,7 +560,7 @@ samplicate (ctx)
 	}
       if (len != sizeof remote_address)
 	{
-	  fprintf (stderr, "recvfrom() return address length %d - expected %d\n",
+	  fprintf (stderr, "recvfrom() return address length %d - expected %zu\n",
 		   len, sizeof remote_address);
 	  exit (1);
 	}
