diff --git a/include/cppast/cpp_variable_base.hpp b/include/cppast/cpp_variable_base.hpp
new file mode 100644
index 0000000..98b54c4
--- /dev/null
+++ b/include/cppast/cpp_variable_base.hpp
@@ -0,0 +1,46 @@
+// Copyright (C) 2017 Jonathan Müller <jonathanmueller.dev@gmail.com>
+// This file is subject to the license terms in the LICENSE file
+// found in the top-level directory of this distribution.
+
+#ifndef CPPAST_CPP_VARIABLE_BASE_HPP_INCLUDED
+#define CPPAST_CPP_VARIABLE_BASE_HPP_INCLUDED
+
+#include <cppast/cpp_entity.hpp>
+#include <cppast/cpp_expression.hpp>
+#include <cppast/cpp_type.hpp>
+
+namespace cppast
+{
+    /// Base class for all [cppast::cpp_entity]() modelling some kind of variable.
+    ///
+    /// Examples are [cppast::cpp_variable]() or [cppast::cpp_function_parameter](),
+    /// or anything that is name/type/default-value triple.
+    class cpp_variable_base : public cpp_entity
+    {
+    public:
+        /// \returns A reference to the [cppast::cpp_type]() of the variable.
+        const cpp_type& type() const noexcept
+        {
+            return *type_;
+        }
+
+        /// \returns A [ts::optional_ref]() to the [cppast::cpp_expression]() that is the default value.
+        type_safe::optional_ref<const cpp_expression> default_value() const noexcept
+        {
+            return *default_;
+        }
+
+    protected:
+        cpp_variable_base(std::string name, std::unique_ptr<cpp_type> type,
+                          std::unique_ptr<cpp_expression> def)
+        : cpp_entity(std::move(name)), type_(std::move(type)), default_(std::move(def))
+        {
+        }
+
+    private:
+        std::unique_ptr<cpp_type>       type_;
+        std::unique_ptr<cpp_expression> default_;
+    };
+} // namespace cppast
+
+#endif // CPPAST_CPP_VARIABLE_BASE_HPP_INCLUDED
diff --git a/include/cppast/visitor.hpp b/include/cppast/visitor.hpp
index 1744392..243a0f5 100644
--- a/include/cppast/visitor.hpp
+++ b/include/cppast/visitor.hpp
@@ -12,7 +12,7 @@ namespace cppast
     /// Information about the state of a visit operation.
     enum class visitor_info
     {
-        leave_entity, //< Callback called for a leave entity without children.
+        leaf_entity, //< Callback called for a leaf entity without children.
 
         container_entity_enter, //< Callback called for a container entity before the children.
         container_entity_exit,  //< Callback called for a container entity after the children.
diff --git a/include/cppast/cpp_type_alias.cpp b/src/cpp_type_alias.cpp
similarity index 100%
rename from include/cppast/cpp_type_alias.cpp
rename to src/cpp_type_alias.cpp
diff --git a/src/visitor.cpp b/src/visitor.cpp
index 2a17259..e42e11c 100644
--- a/src/visitor.cpp
+++ b/src/visitor.cpp
@@ -47,7 +47,7 @@ bool detail::visit(const cpp_entity& e, detail::visitor_callback_t cb, void* fun
     case cpp_entity_kind::using_declaration_t:
     case cpp_entity_kind::type_alias_t:
     case cpp_entity_kind::enum_value_t:
-        return cb(functor, e, visitor_info::leave_entity);
+        return cb(functor, e, visitor_info::leaf_entity);
 
     case cpp_entity_kind::count:
         break;