diff --git a/src/libraries/turtle/is_functor.hpp b/src/libraries/turtle/is_functor.hpp
index 0b038a8..14d088d 100644
--- a/src/libraries/turtle/is_functor.hpp
+++ b/src/libraries/turtle/is_functor.hpp
@@ -31,8 +31,8 @@ namespace detail
     };
 
     MOCK_IS_FUNCTION_HELPER( has_result_type, result_type )
-    MOCK_IS_FUNCTION_HELPER( has_sig, template sig< void > )
-    MOCK_IS_FUNCTION_HELPER( has_result, template result< void > )
+    MOCK_IS_FUNCTION_HELPER( has_sig, BOOST_NESTED_TEMPLATE sig< void > )
+    MOCK_IS_FUNCTION_HELPER( has_result, BOOST_NESTED_TEMPLATE result< void > )
 
 #undef MOCK_IS_FUNCTION_HELPER
 
diff --git a/src/tests/turtle_test/is_functor_test.cpp b/src/tests/turtle_test/is_functor_test.cpp
index be3c4ba..868d276 100644
--- a/src/tests/turtle_test/is_functor_test.cpp
+++ b/src/tests/turtle_test/is_functor_test.cpp
@@ -92,6 +92,7 @@ BOOST_AUTO_TEST_CASE( boost_lambda_is_functor )
 BOOST_AUTO_TEST_CASE( boost_phoenix_is_functor )
 {
     check( boost::phoenix::arg_names::arg1 < 42 );
+    check( boost::phoenix::arg_names::_1 < 42 );
 }
 
 BOOST_AUTO_TEST_CASE( boost_function_is_functor )