diff --git a/include/plasp/pddl/Problem.h b/include/plasp/pddl/Problem.h
index 5b6dc4f..c731853 100644
--- a/include/plasp/pddl/Problem.h
+++ b/include/plasp/pddl/Problem.h
@@ -33,7 +33,7 @@ class Problem
 
 		const Requirements &requirements() const;
 		bool hasRequirement(Requirement::Type requirementType) const;
-		void checkRequirement(Requirement::Type requirementType) const;
+		void checkRequirement(Requirement::Type requirementType);
 
 		expressions::Constants &objects();
 		const expressions::Constants &objects() const;
diff --git a/src/plasp/pddl/Problem.cpp b/src/plasp/pddl/Problem.cpp
index 7aecb00..8a2799e 100644
--- a/src/plasp/pddl/Problem.cpp
+++ b/src/plasp/pddl/Problem.cpp
@@ -254,12 +254,14 @@ bool Problem::hasRequirement(Requirement::Type requirementType) const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Problem::checkRequirement(Requirement::Type requirementType) const
+void Problem::checkRequirement(Requirement::Type requirementType)
 {
 	if (hasRequirement(requirementType))
 		return;
 
-	throw ConsistencyException("requirement “" + Requirement(requirementType).toPDDL() + "” used but never declared");
+	m_context.logger.logWarning(m_context.parser.coordinate(), "requirement “" + Requirement(requirementType).toPDDL() + "” used but never declared");
+
+	m_requirements.push_back(requirementType);
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////