diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 80ca177e7dc4..4a20ad942f5f 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,8 @@
+2016-09-27  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/debug/safe_iterator.h (_Safe_iterator::operator++()): Fix
+	lifetime of lock.
+
 2016-09-20  Jonathan Wakely  <jwakely@redhat.com>
 
 	* python/libstdcxx/v6/xmethods.py (DequeWorkerBase.__init__)
diff --git a/libstdc++-v3/include/debug/safe_iterator.h b/libstdc++-v3/include/debug/safe_iterator.h
index 1eea238b97ac..6e3113ae4244 100644
--- a/libstdc++-v3/include/debug/safe_iterator.h
+++ b/libstdc++-v3/include/debug/safe_iterator.h
@@ -329,7 +329,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 			      _M_message(__msg_bad_inc)
 			      ._M_iterator(*this, "this"));
-	__gnu_cxx::__scoped_lock(this->_M_get_mutex());
+	__gnu_cxx::__scoped_lock __l(this->_M_get_mutex());
 	++base();
 	return *this;
       }