diff --git a/frontends/ast/genrtlil.cc b/frontends/ast/genrtlil.cc
index fe67f00c6..8eb7e2679 100644
--- a/frontends/ast/genrtlil.cc
+++ b/frontends/ast/genrtlil.cc
@@ -2087,8 +2087,6 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 			check_unique_id(current_module, id, this, "cell");
 			RTLIL::Cell *cell = current_module->addCell(id, "");
 			set_src_attr(cell, this);
-			// Set attribute 'module_not_derived' which will be cleared again after the hierarchy pass
-			cell->set_bool_attribute(ID::module_not_derived);
 
 			for (auto it = children.begin(); it != children.end(); it++) {
 				AstNode *child = *it;
@@ -2151,6 +2149,11 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 				}
 				log_abort();
 			}
+
+			// Set attribute 'module_not_derived' which will be cleared again after the hierarchy pass
+			if (cell->type.isPublic())
+				cell->set_bool_attribute(ID::module_not_derived);
+
 			for (auto &attr : attributes) {
 				if (attr.second->type != AST_CONSTANT)
 					input_error("Attribute `%s' with non-constant value.\n", attr.first.c_str());