diff --git a/include/plasp/sas/Operator.h b/include/plasp/sas/Operator.h
index 7fa4d2a..08eb41b 100644
--- a/include/plasp/sas/Operator.h
+++ b/include/plasp/sas/Operator.h
@@ -40,6 +40,8 @@ class Operator
 		size_t costs() const;
 
 	private:
+		Operator() = default;
+
 		Predicate m_predicate;
 		Conditions m_preconditions;
 		Effects m_effects;