diff --git a/include/plasp/pddl/ExpressionContext.h b/include/plasp/pddl/ExpressionContext.h
index 20bb013..983baee 100644
--- a/include/plasp/pddl/ExpressionContext.h
+++ b/include/plasp/pddl/ExpressionContext.h
@@ -3,6 +3,7 @@
 
 #include <plasp/pddl/Expression.h>
 #include <plasp/pddl/Requirement.h>
+#include <plasp/pddl/VariableStack.h>
 
 namespace plasp
 {
@@ -18,8 +19,8 @@ namespace pddl
 class ExpressionContext
 {
 	public:
-		ExpressionContext(Domain &domain, expressions::Variables &parameters);
-		ExpressionContext(Domain &domain, Problem *problem, expressions::Variables &parameters);
+		ExpressionContext(Domain &domain);
+		ExpressionContext(Domain &domain, Problem *problem);
 
 		bool hasRequirement(Requirement::Type requirementType) const;
 		void checkRequirement(Requirement::Type requirementType) const;
@@ -27,7 +28,7 @@ class ExpressionContext
 		Domain &domain;
 		Problem *problem;
 
-		expressions::Variables &parameters;
+		VariableStack variables;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/plasp/pddl/VariableStack.h b/include/plasp/pddl/VariableStack.h
new file mode 100644
index 0000000..452902f
--- /dev/null
+++ b/include/plasp/pddl/VariableStack.h
@@ -0,0 +1,34 @@
+#ifndef __PLASP__PDDL__VARIABLE_STACK_H
+#define __PLASP__PDDL__VARIABLE_STACK_H
+
+#include <plasp/pddl/expressions/Variable.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// VariableStack
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class VariableStack
+{
+	public:
+		void push(expressions::Variables *variables);
+		void pop();
+
+		expressions::VariablePointer parseAndFind(Context &context);
+
+	private:
+		std::vector<expressions::Variables *> m_variableStack;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/include/plasp/pddl/expressions/Variable.h b/include/plasp/pddl/expressions/Variable.h
index 3c7ba63..654d0b4 100644
--- a/include/plasp/pddl/expressions/Variable.h
+++ b/include/plasp/pddl/expressions/Variable.h
@@ -26,9 +26,6 @@ class Variable: public ExpressionCRTP<Variable>
 		static void parseTypedDeclarations(Context &context, ExpressionContext &expressionContext,
 			Variables &variables);
 
-		static VariablePointer parseAndFind(Context &context,
-			const ExpressionContext &expressionContext);
-
 	public:
 		void setName(std::string name);
 		const std::string &name() const;
diff --git a/src/plasp/pddl/Action.cpp b/src/plasp/pddl/Action.cpp
index 2bbb7df..657b68a 100644
--- a/src/plasp/pddl/Action.cpp
+++ b/src/plasp/pddl/Action.cpp
@@ -29,7 +29,8 @@ void Action::parseDeclaration(Context &context, Domain &domain)
 	parser.expect<std::string>(":parameters");
 	parser.expect<std::string>("(");
 
-	ExpressionContext expressionContext(domain, action->m_parameters);
+	ExpressionContext expressionContext(domain);
+	expressionContext.variables.push(&action->m_parameters);
 
 	// Read parameters
 	expressions::Variable::parseTypedDeclarations(context, expressionContext, action->m_parameters);
diff --git a/src/plasp/pddl/ExpressionContext.cpp b/src/plasp/pddl/ExpressionContext.cpp
index ed3fb97..25b2275 100644
--- a/src/plasp/pddl/ExpressionContext.cpp
+++ b/src/plasp/pddl/ExpressionContext.cpp
@@ -14,19 +14,17 @@ namespace pddl
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-ExpressionContext::ExpressionContext(Domain &domain, expressions::Variables &parameters)
+ExpressionContext::ExpressionContext(Domain &domain)
 :	domain(domain),
-	problem(nullptr),
-	parameters(parameters)
+	problem(nullptr)
 {
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-ExpressionContext::ExpressionContext(Domain &domain, Problem *problem, expressions::Variables &parameters)
+ExpressionContext::ExpressionContext(Domain &domain, Problem *problem)
 :	domain(domain),
-	problem{problem},
-	parameters(parameters)
+	problem{problem}
 {
 }
 
diff --git a/src/plasp/pddl/Problem.cpp b/src/plasp/pddl/Problem.cpp
index 5673b22..f4d38fd 100644
--- a/src/plasp/pddl/Problem.cpp
+++ b/src/plasp/pddl/Problem.cpp
@@ -333,9 +333,7 @@ void Problem::parseInitialStateSection()
 	parser.expect<std::string>(":");
 	parser.expect<std::string>("init");
 
-	// TODO: remove workaround
-	expressions::Variables noParameters;
-	ExpressionContext expressionContext(m_domain, this, noParameters);
+	ExpressionContext expressionContext(m_domain, this);
 
 	m_initialState = InitialState::parseDeclaration(m_context, expressionContext);
 
@@ -352,9 +350,7 @@ void Problem::parseGoalSection()
 	parser.expect<std::string>(":");
 	parser.expect<std::string>("goal");
 
-	// TODO: remove workaround
-	expressions::Variables noParameters;
-	ExpressionContext expressionContext(m_domain, this, noParameters);
+	ExpressionContext expressionContext(m_domain, this);
 
 	m_goal = parsePreconditionExpression(m_context, expressionContext);
 
diff --git a/src/plasp/pddl/VariableStack.cpp b/src/plasp/pddl/VariableStack.cpp
new file mode 100644
index 0000000..54d0f35
--- /dev/null
+++ b/src/plasp/pddl/VariableStack.cpp
@@ -0,0 +1,62 @@
+#include <plasp/pddl/VariableStack.h>
+
+#include <plasp/pddl/Context.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// VariableStack
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void VariableStack::push(expressions::Variables *variables)
+{
+	m_variableStack.push_back(variables);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void VariableStack::pop()
+{
+	m_variableStack.pop_back();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+expressions::VariablePointer VariableStack::parseAndFind(plasp::pddl::Context &context)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	parser.expect<std::string>("?");
+
+	const auto variableName = parser.parseIdentifier();
+
+	for (auto i = m_variableStack.crbegin(); i != m_variableStack.crend(); i++)
+	{
+		const auto *variables = *i;
+
+		BOOST_ASSERT(variables);
+
+		const auto match = std::find_if(variables->crbegin(), variables->crend(),
+			[&](const auto &variable)
+			{
+				return variable->name() == variableName;
+			});
+
+		if (match != variables->crend())
+			return match->get();
+	}
+
+	throw utils::ParserException(parser.coordinate(), "variable “" + variableName + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/src/plasp/pddl/expressions/Predicate.cpp b/src/plasp/pddl/expressions/Predicate.cpp
index 0e40cbc..fc10da9 100644
--- a/src/plasp/pddl/expressions/Predicate.cpp
+++ b/src/plasp/pddl/expressions/Predicate.cpp
@@ -66,7 +66,7 @@ PredicatePointer Predicate::parse(Context &context, ExpressionContext &expressio
 		// Parse variables
 		if (context.parser.currentCharacter() == '?')
 		{
-			const auto variable = Variable::parseAndFind(context, expressionContext);
+			const auto variable = expressionContext.variables.parseAndFind(context);
 			predicate->m_arguments.emplace_back(variable);
 		}
 		// Parse constants
diff --git a/src/plasp/pddl/expressions/PredicateDeclaration.cpp b/src/plasp/pddl/expressions/PredicateDeclaration.cpp
index fec9d1e..b492a1c 100644
--- a/src/plasp/pddl/expressions/PredicateDeclaration.cpp
+++ b/src/plasp/pddl/expressions/PredicateDeclaration.cpp
@@ -39,7 +39,8 @@ void PredicateDeclaration::parse(Context &context, Domain &domain)
 
 	context.parser.skipWhiteSpace();
 
-	ExpressionContext expressionContext(domain, predicate->m_parameters);
+	ExpressionContext expressionContext(domain);
+	expressionContext.variables.push(&predicate->m_parameters);
 
 	// Parse arguments
 	expressions::Variable::parseTypedDeclarations(context, expressionContext, predicate->m_parameters);
diff --git a/src/plasp/pddl/expressions/Variable.cpp b/src/plasp/pddl/expressions/Variable.cpp
index 7609588..67a72a8 100644
--- a/src/plasp/pddl/expressions/Variable.cpp
+++ b/src/plasp/pddl/expressions/Variable.cpp
@@ -136,32 +136,6 @@ void Variable::parseTypedDeclarations(Context &context, ExpressionContext &expre
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-VariablePointer Variable::parseAndFind(Context &context, const ExpressionContext &expressionContext)
-{
-	auto &parser = context.parser;
-
-	parser.skipWhiteSpace();
-
-	parser.expect<std::string>("?");
-
-	const auto variableName = parser.parseIdentifier();
-
-	const auto &variables = expressionContext.parameters;
-
-	const auto match = std::find_if(variables.cbegin(), variables.cend(),
-		[&](const auto &variable)
-		{
-			return variable->name() == variableName;
-		});
-
-	if (match == variables.cend())
-		throw utils::ParserException(parser.coordinate(), "parameter “" + variableName + "” used but never declared");
-
-	return match->get();
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
 void Variable::setName(std::string name)
 {
 	m_name = name;