diff --git a/examples/demo.cpp b/examples/demo.cpp
index ae14c60..04df3ee 100644
--- a/examples/demo.cpp
+++ b/examples/demo.cpp
@@ -2,17 +2,6 @@
 
 #include <iostream>
 
-#include <boost/lexical_cast.hpp>
-
-namespace string2type {
-
-template<>
-int convert<int>(const std::string &value) {
-    return boost::lexical_cast<int>(value);
-}
-
-}
-
 struct foo : attributes {
     foo() {
         REGISTER_ATTRIBUTE(int, x);
diff --git a/src/string2type.hpp b/src/string2type.hpp
index 044b842..332a48c 100644
--- a/src/string2type.hpp
+++ b/src/string2type.hpp
@@ -16,10 +16,14 @@
 
 #include <string>
 
+#include <boost/lexical_cast.hpp>
+
 namespace string2type {
 
 template<typename T>
-T convert(const std::string &value);
+T convert(const std::string &value) {
+    return boost::lexical_cast<T>(value);
+}
 
 }
 
diff --git a/unittest/AttributesTest.cpp b/unittest/AttributesTest.cpp
index 49573eb..d8296ba 100644
--- a/unittest/AttributesTest.cpp
+++ b/unittest/AttributesTest.cpp
@@ -6,16 +6,6 @@
 #include <boost/test/unit_test.hpp>
 
 #include <iostream>
-#include <boost/lexical_cast.hpp>
-
-namespace string2type {
-
-template<>
-int convert<int>(const std::string &value) {
-    return boost::lexical_cast<int>(value);
-}
-
-}
 
 struct test : attributes {
     test() : x(0) {
diff --git a/unittest/String2typeTest.cpp b/unittest/String2typeTest.cpp
index 880870f..459a8f8 100644
--- a/unittest/String2typeTest.cpp
+++ b/unittest/String2typeTest.cpp
@@ -5,23 +5,6 @@
 
 #include <boost/test/unit_test.hpp>
 
-#include <iostream>
-#include <boost/lexical_cast.hpp>
-
-namespace string2type {
-
-template<>
-int convert<int>(const std::string &value) {
-    return boost::lexical_cast<int>(value);
-}
-
-template<>
-double convert<double>(const std::string &value) {
-    return boost::lexical_cast<double>(value);
-}
-
-}
-
 BOOST_AUTO_TEST_SUITE(string2type_test)
 
 BOOST_AUTO_TEST_CASE( test1 )