diff --git a/src/ifcwrap/IfcParseWrapper.i b/src/ifcwrap/IfcParseWrapper.i
index 63f5fc8ba6..261f3c9da9 100644
--- a/src/ifcwrap/IfcParseWrapper.i
+++ b/src/ifcwrap/IfcParseWrapper.i
@@ -623,6 +623,12 @@ private:
 			// @nb we don't check anymore if the attribute is optional here, because it should be
 			// possible to go back to the state at construction time.
 			// bool is_optional = $self->declaration().as_entity()->attribute_by_index(i)->optional();
+			// A derived attribute keeps its derived marker, as at construction time.
+			auto* ent = $self->declaration().as_entity();
+			if (ent && i < ent->derived().size() && ent->derived()[i]) {
+				self->set_attribute_value(i, ifcopenshell::derived{});
+				return;
+			}
 			self->set_attribute_value(i, blank{});
 			return;
 		}