diff --git a/extlib/benz/codegen.c b/extlib/benz/codegen.c
index 44895678..3d1f94c6 100644
--- a/extlib/benz/codegen.c
+++ b/extlib/benz/codegen.c
@@ -811,7 +811,6 @@ codegen_set(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
   type = pic_sym_ptr(pic_list_ref(pic, var, 0));
   if (type == pic->sGREF) {
     emit_i(pic, cxt, OP_GSET, index_symbol(pic, cxt, pic_sym_ptr(pic_list_ref(pic, var, 1))));
-    emit_n(pic, cxt, OP_PUSHUNDEF);
     emit_ret(pic, cxt, tailpos);
   }
   else if (type == pic->sCREF) {
@@ -821,7 +820,6 @@ codegen_set(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
     depth = pic_int(pic_list_ref(pic, var, 1));
     name  = pic_sym_ptr(pic_list_ref(pic, var, 2));
     emit_r(pic, cxt, OP_CSET, depth, index_capture(cxt, name, depth));
-    emit_n(pic, cxt, OP_PUSHUNDEF);
     emit_ret(pic, cxt, tailpos);
   }
   else if (type == pic->sLREF) {
@@ -831,11 +829,9 @@ codegen_set(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
     name = pic_sym_ptr(pic_list_ref(pic, var, 1));
     if ((i = index_capture(cxt, name, 0)) != -1) {
       emit_i(pic, cxt, OP_LSET, i + (int)cxt->args->len + (int)cxt->locals->len + 1);
-      emit_n(pic, cxt, OP_PUSHUNDEF);
       emit_ret(pic, cxt, tailpos);
     } else {
       emit_i(pic, cxt, OP_LSET, index_local(cxt, name));
-      emit_n(pic, cxt, OP_PUSHUNDEF);
       emit_ret(pic, cxt, tailpos);
     }
   }
diff --git a/extlib/benz/vm.c b/extlib/benz/vm.c
index 58a7acf9..d1cffea1 100644
--- a/extlib/benz/vm.c
+++ b/extlib/benz/vm.c
@@ -643,6 +643,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
 
       val = POP();
       pic_dict_set(pic, pic->globals, sym, val);
+      PUSH(pic_undef_value());
       NEXT;
     }
     CASE(OP_LREF) {
@@ -671,6 +672,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
         }
       }
       pic->ci->fp[c.u.i] = POP();
+      PUSH(pic_undef_value());
       NEXT;
     }
     CASE(OP_CREF) {
@@ -693,6 +695,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
 	cxt = cxt->up;
       }
       cxt->regs[c.u.r.idx] = POP();
+      PUSH(pic_undef_value());
       NEXT;
     }
     CASE(OP_JMP) {