diff --git a/include/fc/rpc/api_connection.hpp b/include/fc/rpc/api_connection.hpp
index 1345c45..9045207 100644
--- a/include/fc/rpc/api_connection.hpp
+++ b/include/fc/rpc/api_connection.hpp
@@ -146,7 +146,7 @@ namespace fc {
             return f();
          }
 
-         template<typename R, typename Signature, typename ... Args>
+         template<typename R, typename Signature, typename ... Args, typename std::enable_if<std::is_function<Signature>::value,Signature>::type* = nullptr>
          R call_generic( const std::function<R(std::function<Signature>,Args...)>& f, variants::const_iterator a0, variants::const_iterator e, uint32_t max_depth )
          {
             FC_ASSERT( a0 != e, "too few arguments passed to method" );
@@ -154,7 +154,7 @@ namespace fc {
             detail::callback_functor<Signature> arg0( get_connection(), a0->as<uint64_t>(1) );
             return call_generic<R,Args...>( this->bind_first_arg<R,std::function<Signature>,Args...>( f, std::function<Signature>(arg0) ), a0+1, e, max_depth - 1 );
          }
-         template<typename R, typename Signature, typename ... Args>
+         template<typename R, typename Signature, typename ... Args, typename std::enable_if<std::is_function<Signature>::value,Signature>::type* = nullptr>
          R call_generic( const std::function<R(const std::function<Signature>&,Args...)>& f, variants::const_iterator a0, variants::const_iterator e, uint32_t max_depth )
          {
             FC_ASSERT( a0 != e, "too few arguments passed to method" );