diff --git a/src/ast/sls/sls_bv_eval.cpp b/src/ast/sls/sls_bv_eval.cpp
index a68a3a6339..532cebe420 100644
--- a/src/ast/sls/sls_bv_eval.cpp
+++ b/src/ast/sls/sls_bv_eval.cpp
@@ -315,7 +315,7 @@ namespace sls {
                 val.set(val_el.bits());
             return;
         }
-        if (e->get_family_id() == null_family_id) {
+        if (e->get_family_id() != bv.get_fid()) {
             val.set(wval(e).bits());
             return;
         }