diff --git a/include/boost/serialization/singleton.hpp b/include/boost/serialization/singleton.hpp
index cce2d26e..b9d4fa0f 100644
--- a/include/boost/serialization/singleton.hpp
+++ b/include/boost/serialization/singleton.hpp
@@ -87,9 +87,17 @@ class BOOST_SYMBOL_VISIBLE singleton_module :
 private:
     static bool & get_lock();
 public:
-    BOOST_SERIALIZATION_DECL static void lock();
-    BOOST_SERIALIZATION_DECL static void unlock();
-    BOOST_SERIALIZATION_DECL static bool is_locked();
+    BOOST_SERIALIZATION_DECL static void lock(){
+        get_lock() = true;
+    }
+
+    BOOST_SERIALIZATION_DECL static void unlock(){
+        get_lock() = false;
+    }
+
+    BOOST_SERIALIZATION_DECL static bool is_locked(){
+        return get_lock();
+    }
 };
 
 #include <boost/archive/detail/abi_suffix.hpp> // pops abi_suffix.hpp pragmas
diff --git a/src/singleton.cpp b/src/singleton.cpp
index b8078c1b..731c9aff 100644
--- a/src/singleton.cpp
+++ b/src/singleton.cpp
@@ -22,15 +22,17 @@ bool & singleton_module::get_lock(){
     return lock;
 }
 
+#if 0
 BOOST_SERIALIZATION_DECL void singleton_module::lock(){
     get_lock() = true;
 }
 BOOST_SERIALIZATION_DECL void singleton_module::unlock(){
     get_lock() = false;
 }
-BOOST_SERIALIZATION_DECL bool singleton_module::is_locked() {
+BOOST_SERIALIZATION_DECL bool singleton_module::is_locked(){
     return get_lock();
 }
+#endif
 
 } // namespace serialization
 } // namespace boost