diff --git a/ivl.def b/ivl.def
index 2cd13ee63..17c16f091 100644
--- a/ivl.def
+++ b/ivl.def
@@ -5,6 +5,7 @@ ivl_design_consts
 ivl_design_flag
 ivl_design_process
 ivl_design_root
+ivl_design_roots
 ivl_design_time_precision
 
 ivl_const_bits