diff --git a/src/muz/rel/dl_compiler.cpp b/src/muz/rel/dl_compiler.cpp
index 860add434..204a8f316 100644
--- a/src/muz/rel/dl_compiler.cpp
+++ b/src/muz/rel/dl_compiler.cpp
@@ -633,12 +633,8 @@ namespace datalog {
 
         // add at least one column for the negative filter
         if (pt_len != ut_len && filtered_res == execution_context::void_register) {
-            relation_signature & head_sig = m_reg_signatures[head_reg];
-            if (head_sig.empty()) {
-                make_full_relation(head_pred, m_reg_signatures[head_reg], filtered_res, acc);
-            } else {
-                make_add_unbound_column(r, 0, head_pred, filtered_res, head_sig[0], filtered_res, dealloc, acc);
-            }
+            relation_signature empty_signature;
+            make_full_relation(head_pred, empty_signature, filtered_res, acc);
         }
 
         //enforce negative predicates