diff --git a/libcxx/docs/Status/Cxx2bIssues.csv b/libcxx/docs/Status/Cxx2bIssues.csv
--- a/libcxx/docs/Status/Cxx2bIssues.csv
+++ b/libcxx/docs/Status/Cxx2bIssues.csv
@@ -11,7 +11,7 @@
 "`3447 <https://wg21.link/LWG3447>`__","Deduction guides for ``take_view`` and ``drop_view`` have different constraints","November 2020","|Complete|","14.0"
 "`3450 <https://wg21.link/LWG3450>`__","The const overloads of ``take_while_view::begin/end`` are underconstrained","November 2020","","","|ranges|"
 "`3464 <https://wg21.link/LWG3464>`__","``istream::gcount()`` can overflow","November 2020","",""
-"`2731 <https://wg21.link/LWG2731>`__","Existence of ``lock_guard<MutexTypes...>::mutex_type`` typedef unclear","November 2020","",""
+"`2731 <https://wg21.link/LWG2731>`__","Existence of ``lock_guard<MutexTypes...>::mutex_type`` typedef unclear","November 2020","|Complete|","5.0"
 "`2743 <https://wg21.link/LWG2743>`__","P0083R3 ``node_handle`` private members missing ""exposition only"" comment","November 2020","",""
 "`2820 <https://wg21.link/LWG2820>`__","Clarify ``<cstdint>`` macros","November 2020","",""
 "`3120 <https://wg21.link/LWG3120>`__","Unclear behavior of ``monotonic_buffer_resource::release()``","November 2020","",""
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -112,7 +112,7 @@
 class scoped_lock // C++17
 {
 public:
-    using mutex_type = Mutex;  // If MutexTypes... consists of the single type Mutex
+    using mutex_type = Mutex;  // Only if sizeof...(MutexTypes) == 1
 
     explicit scoped_lock(MutexTypes&... m);
     scoped_lock(adopt_lock_t, MutexTypes&... m);
diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/types.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/types.pass.cpp
--- a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/types.pass.cpp
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/types.pass.cpp
@@ -11,11 +11,11 @@
 
 // <mutex>
 
-// template <class Mutex...>
+// template <class... MutexTypes>
 // class scoped_lock
 // {
 // public:
-//     typedef Mutex mutex_type;  // only if sizeof...(Mutex) == 1
+//     typedef Mutex mutex_type;  // Only if sizeof...(MutexTypes) == 1
 //     ...
 // };