diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index 7be7005..f40a99e 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -348,6 +348,12 @@ class generic_error_category: public error_category
 {
 public:
 
+    // clang++ 3.8 and below: initialization of const object
+    // requires a user-provided default constructor
+    BOOST_SYSTEM_CONSTEXPR generic_error_category() BOOST_SYSTEM_NOEXCEPT
+    {
+    }
+
     const char * name() const BOOST_SYSTEM_NOEXCEPT
     {
         return "generic";
@@ -360,6 +366,10 @@ class system_error_category: public error_category
 {
 public:
 
+    BOOST_SYSTEM_CONSTEXPR system_error_category() BOOST_SYSTEM_NOEXCEPT
+    {
+    }
+
     const char * name() const BOOST_SYSTEM_NOEXCEPT
     {
         return "system";