diff --git a/include/boost/detail/lwm_nop.hpp b/include/boost/detail/lwm_nop.hpp
index 1d798e0..671a5b0 100644
--- a/include/boost/detail/lwm_nop.hpp
+++ b/include/boost/detail/lwm_nop.hpp
@@ -24,30 +24,9 @@ namespace detail
 
 class lightweight_mutex
 {
-private:
-
-    lightweight_mutex(lightweight_mutex const &);
-    lightweight_mutex & operator=(lightweight_mutex const &);
-
 public:
 
-    lightweight_mutex()
-    {
-    }
-
-    class scoped_lock
-    {
-    private:
-
-        scoped_lock(scoped_lock const &);
-        scoped_lock & operator=(scoped_lock const &);
-
-    public:
-
-        explicit scoped_lock(lightweight_mutex &)
-        {
-        }
-    };
+    typedef lightweight_mutex scoped_lock;
 };
 
 } // namespace detail
diff --git a/include/boost/detail/shared_count.hpp b/include/boost/detail/shared_count.hpp
index d513329..9dfed4f 100644
--- a/include/boost/detail/shared_count.hpp
+++ b/include/boost/detail/shared_count.hpp
@@ -74,7 +74,9 @@ public:
 
     void add_ref()
     {
+#ifdef BOOST_HAS_THREADS
         lightweight_mutex::scoped_lock lock(mtx_);
+#endif
         if(use_count_ == 0) throw use_count_is_zero();
         ++use_count_;
         ++weak_count_;
@@ -86,7 +88,9 @@ public:
         long new_weak_count;
 
         {
+#ifdef BOOST_HAS_THREADS
             lightweight_mutex::scoped_lock lock(mtx_);
+#endif
             new_use_count = --use_count_;
             new_weak_count = --weak_count_;
         }
@@ -106,7 +110,9 @@ public:
 
     void weak_add_ref() // nothrow
     {
+#ifdef BOOST_HAS_THREADS
         lightweight_mutex::scoped_lock lock(mtx_);
+#endif
         ++weak_count_;
     }
 
@@ -115,7 +121,9 @@ public:
         long new_weak_count;
 
         {
+#ifdef BOOST_HAS_THREADS
             lightweight_mutex::scoped_lock lock(mtx_);
+#endif
             new_weak_count = --weak_count_;
         }
 
@@ -127,7 +135,9 @@ public:
 
     long use_count() const // nothrow
     {
+#ifdef BOOST_HAS_THREADS
         lightweight_mutex::scoped_lock lock(mtx_);
+#endif
         return use_count_;
     }
 
@@ -145,7 +155,9 @@ private:
 
     long use_count_;
     long weak_count_;
+#ifdef BOOST_HAS_THREADS
     mutable lightweight_mutex mtx_;
+#endif
     void (*self_deleter_) (counted_base *);
 };