diff --git a/src/vnet/fib/mpls_fib.c b/src/vnet/fib/mpls_fib.c
index 34369fc..5dcd70b 100644
--- a/src/vnet/fib/mpls_fib.c
+++ b/src/vnet/fib/mpls_fib.c
@@ -451,7 +451,7 @@
 	    continue;
 
 	s = format (s, "%v, fib_index:%d locks:[",
-                    fib_table->ft_desc, mpls_main.fibs - fib_table);
+                    fib_table->ft_desc, fib_table - mpls_main.fibs);
         vec_foreach_index(source, fib_table->ft_locks)
         {
             if (0 != fib_table->ft_locks[source])