diff --git a/src/ifcgeom/mapping/IfcCurveSegment.cpp b/src/ifcgeom/mapping/IfcCurveSegment.cpp
index bfe8a191ca..241c3eb106 100644
--- a/src/ifcgeom/mapping/IfcCurveSegment.cpp
+++ b/src/ifcgeom/mapping/IfcCurveSegment.cpp
@@ -67,7 +67,7 @@ double translate_if_param_value(const IfcSchema::IfcCurve* crv, IfcSchema::IfcCu
         // We don't care whether length- or positive length measure.
         return translate_to_length_measure(crv, *param);
     } else {
-        return val->data().get_attribute_value(0);
+        return val->as<IfcUtil::IfcBaseClass>()->get_attribute_value(0);
     }
 }