diff --git a/include/chaiscript/dispatchkit/callable_traits.hpp b/include/chaiscript/dispatchkit/callable_traits.hpp
index 4b61b088..8d7936d2 100644
--- a/include/chaiscript/dispatchkit/callable_traits.hpp
+++ b/include/chaiscript/dispatchkit/callable_traits.hpp
@@ -25,10 +25,10 @@ namespace chaiscript {
       template<typename Ret, typename Class, typename ... Param>
       struct Const_Caller
       {
-        explicit Const_Caller(Ret (Class::*t_func)(Param...) const) : m_func(t_func) {}
+        constexpr explicit Const_Caller(Ret (Class::*t_func)(Param...) const) : m_func(t_func) {}
 
         template<typename ... Inner>
-        Ret operator()(const Class &o, Inner&& ... inner) const {
+        constexpr Ret operator()(const Class &o, Inner&& ... inner) const {
           return (o.*m_func)(std::forward<Inner>(inner)...);
         }
 
@@ -38,10 +38,10 @@ namespace chaiscript {
       template<typename Ret, typename ... Param>
       struct Fun_Caller
       {
-        explicit Fun_Caller(Ret( * t_func)(Param...) ) : m_func(t_func) {}
+        constexpr explicit Fun_Caller(Ret( * t_func)(Param...) ) : m_func(t_func) {}
 
         template<typename ... Inner>
-        Ret operator()(Inner&& ... inner) const {
+        constexpr Ret operator()(Inner&& ... inner) const {
           return (m_func)(std::forward<Inner>(inner)...);
         }
 
@@ -51,10 +51,10 @@ namespace chaiscript {
       template<typename Ret, typename Class, typename ... Param>
       struct Caller
       {
-        explicit Caller(Ret (Class::*t_func)(Param...)) : m_func(t_func) {}
+        constexpr explicit Caller(Ret (Class::*t_func)(Param...)) : m_func(t_func) {}
 
         template<typename ... Inner>
-        Ret operator()(Class &o, Inner&& ... inner) const {
+        constexpr Ret operator()(Class &o, Inner&& ... inner) const {
           return (o.*m_func)(std::forward<Inner>(inner)...);
         }