diff --git a/src/plasp/pddl/Action.cpp b/src/plasp/pddl/Action.cpp
index 8e29923..1d86e51 100644
--- a/src/plasp/pddl/Action.cpp
+++ b/src/plasp/pddl/Action.cpp
@@ -92,7 +92,18 @@ void Action::normalize(expressions::DerivedPredicates &derivedPredicates)
 {
 	// Normalize preconditions and effects
 	m_precondition = m_precondition->normalized()->decomposed(derivedPredicates);
+	{
+		// TODO: refactor
+		std::set<expressions::VariablePointer> parameters;
+		m_precondition->collectParameters(parameters);
+	}
+
 	m_effect = m_effect->normalized();
+	{
+		// TODO: refactor
+		std::set<expressions::VariablePointer> parameters;
+		m_effect->collectParameters(parameters);
+	}
 
 	// Normalize parameter names
 	for (size_t i = 0; i < m_parameters.size(); i++)
diff --git a/src/plasp/pddl/TranslatorASP.cpp b/src/plasp/pddl/TranslatorASP.cpp
index f9c00ee..20271c8 100644
--- a/src/plasp/pddl/TranslatorASP.cpp
+++ b/src/plasp/pddl/TranslatorASP.cpp
@@ -235,8 +235,7 @@ void TranslatorASP::translateDerivedPredicates() const
 
 			m_outputStream << "))";
 
-			// TODO: implement
-			//translateVariablesBody(m_outputStream, predicate->arguments());
+			translateVariablesBody(m_outputStream, predicate->parameters());
 
 			m_outputStream << ".";
 		});