diff --git a/vvp/vvp.def b/vvp/vvp.def
index ad3990f05..1ec96567d 100644
--- a/vvp/vvp.def
+++ b/vvp/vvp.def
@@ -37,3 +37,4 @@ vpi_vprintf
 
 vpip_format_strength
 vpip_set_return_value
+vpip_calc_clog2