diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 1c871c0fb29..a59c5d6b9b5 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,11 @@
+2013-05-18  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	* include/std/system_error (error_category::error_category()): LWG
+	2145: Declare public and constexpr.
+	* src/c++11/system_error.cc (error_category::error_category()): Move
+	definition to ...
+	* src/c++11/compatibility-c++0x.cc: Here.
+
 2013-05-18  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
 	* include/std/typeindex (type_index::name()): LWG 2144: Add noexcept.
diff --git a/libstdc++-v3/include/std/system_error b/libstdc++-v3/include/std/system_error
index b63b74e1f93..d66b8714e03 100644
--- a/libstdc++-v3/include/std/system_error
+++ b/libstdc++-v3/include/std/system_error
@@ -65,11 +65,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// error_category
   class error_category
   {
-  protected:
-    error_category() noexcept;
-
   public:
-    virtual ~error_category() noexcept;
+#ifdef _GLIBCXX_COMPATIBILITY_CXX0X
+    error_category() noexcept;
+#else
+    constexpr error_category() noexcept = default;
+#endif
+
+    virtual ~error_category();
 
     error_category(const error_category&) = delete;
     error_category& operator=(const error_category&) = delete;
diff --git a/libstdc++-v3/src/c++11/compatibility-c++0x.cc b/libstdc++-v3/src/c++11/compatibility-c++0x.cc
index fc84a5e23ec..64a4a6c0984 100644
--- a/libstdc++-v3/src/c++11/compatibility-c++0x.cc
+++ b/libstdc++-v3/src/c++11/compatibility-c++0x.cc
@@ -119,6 +119,10 @@ namespace std _GLIBCXX_VISIBILITY(default)
     };
     constexpr bool system_clock::is_monotonic;
   } // namespace chrono
+
+  // gcc-4.9.0
+  // LWG 2145 changes this constructor to constexpr i.e. inline
+  error_category::error_category() noexcept = default;
 }
 
 #endif
diff --git a/libstdc++-v3/src/c++11/system_error.cc b/libstdc++-v3/src/c++11/system_error.cc
index 453c6877b03..65dcef3f134 100644
--- a/libstdc++-v3/src/c++11/system_error.cc
+++ b/libstdc++-v3/src/c++11/system_error.cc
@@ -70,8 +70,6 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-  error_category::error_category() noexcept = default;
-
   error_category::~error_category() noexcept = default;
 
   const error_category&