diff --git a/CMakeLists.txt b/CMakeLists.txt
index c2244e2..beae58f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,6 +60,8 @@ SET(SCULLY_SOURCE
 
     src/AST/ASTElement.cpp
     src/AST/ASTVisitor.cpp
+	src/AST/ConstantExpression.cpp
+	src/AST/Expression.cpp
 	src/AST/ParameterList.cpp
 	src/AST/Statement.cpp
 	src/AST/Type.cpp
diff --git a/grammar/grammar.y b/grammar/grammar.y
index a65cd0f..72f9c3c 100644
--- a/grammar/grammar.y
+++ b/grammar/grammar.y
@@ -8,6 +8,8 @@
 #include "Token.h"
 
 #include "AST/ASTElement.h"
+#include "AST/ConstantExpression.h"
+#include "AST/Expression.h"
 #include "AST/ParameterList.h"
 #include "AST/Statement.h"
 #include "AST/Type.h"
diff --git a/inc/AST/ASTVisitor.h b/inc/AST/ASTVisitor.h
index 8e4ee8e..00c27b2 100644
--- a/inc/AST/ASTVisitor.h
+++ b/inc/AST/ASTVisitor.h
@@ -1,6 +1,7 @@
 #ifndef ASTVISITOR_H
 #define ASTVISITOR_H
 
+#include "ConstantExpression.h"
 #include "VariableDefinition.h"
 #include "ParameterList.h"
 
@@ -9,6 +10,7 @@ public:
 	ASTVisitor();
 	virtual ~ASTVisitor();
 
+	virtual void visit(ConstantExpression* e) = 0;
 	virtual void visit(ParameterList* e) = 0;
 	virtual void visit(VariableDefinition* e) = 0;
 };
diff --git a/inc/AST/ConstantExpression.h b/inc/AST/ConstantExpression.h
new file mode 100644
index 0000000..46daa9f
--- /dev/null
+++ b/inc/AST/ConstantExpression.h
@@ -0,0 +1,19 @@
+#ifndef CONSTANTEXPRESSION_H
+#define CONSTANTEXPRESSION_H
+
+#include "AST/Expression.h"
+#include <string>
+
+class ConstantExpression : public Expression {
+public:
+	ConstantExpression(std::string value);
+	virtual ~ConstantExpression();
+
+	virtual void accept(ASTVisitor* visitor);
+
+	std::string getValue();
+private:
+	std::string value_;
+};
+
+#endif // CONSTANTEXPRESSION_H
diff --git a/inc/AST/Expression.h b/inc/AST/Expression.h
new file mode 100644
index 0000000..0f2fa98
--- /dev/null
+++ b/inc/AST/Expression.h
@@ -0,0 +1,14 @@
+#ifndef EXPRESSION_H
+#define EXPRESSION_H
+
+#include "AST/ASTElement.h"
+
+class Expression : public ASTElement {
+public:
+	Expression();
+	virtual ~Expression();
+
+	virtual void accept(ASTVisitor* visitor) = 0;
+};
+
+#endif // EXPRESSION_H
diff --git a/src/AST/ConstantExpression.cpp b/src/AST/ConstantExpression.cpp
new file mode 100644
index 0000000..5d96fda
--- /dev/null
+++ b/src/AST/ConstantExpression.cpp
@@ -0,0 +1,17 @@
+#include "AST/ConstantExpression.h"
+#include "AST/ASTVisitor.h"
+
+ConstantExpression::ConstantExpression(std::string value) : value_(value) {
+	//
+}
+
+ConstantExpression::~ConstantExpression() {
+}
+
+void ConstantExpression::accept(ASTVisitor* visitor) {
+	visitor->visit(this);
+}
+
+std::string ConstantExpression::getValue() {
+	return value_;
+}
diff --git a/src/AST/Expression.cpp b/src/AST/Expression.cpp
new file mode 100644
index 0000000..6eedb16
--- /dev/null
+++ b/src/AST/Expression.cpp
@@ -0,0 +1,9 @@
+#include "AST/Expression.h"
+
+Expression::Expression() {
+	//
+}
+
+Expression::~Expression() {
+	//
+}