diff --git a/src/lib/frontend/d_cnf.ml b/src/lib/frontend/d_cnf.ml
index 0aed56e5f..377fcda33 100644
--- a/src/lib/frontend/d_cnf.ml
+++ b/src/lib/frontend/d_cnf.ml
@@ -425,6 +425,8 @@ let smt_fpa_builtins =
       end
     | Id { ns = Term ; name = Simple "ae.float16" } ->
       term_app env s (smt_round 11 24)
+    | Id { ns = Term ; name = Simple "bv2int" } ->
+      term_app1 env s DE.Term.Bitv.to_nat
     | Id { ns = Term ; name = Simple "ae.float32" } ->
       term_app env s (smt_round 24 149)
     | Id { ns = Term ; name = Simple "ae.float64" } ->