diff --git a/include/sqlpp11/boolean.h b/include/sqlpp11/boolean.h
index baef620e..66e80853 100644
--- a/include/sqlpp11/boolean.h
+++ b/include/sqlpp11/boolean.h
@@ -42,6 +42,7 @@ namespace sqlpp
 		// boolean value type
 		struct boolean
 		{
+			using _value_type = boolean;
 			using _base_value_type = boolean;
 			using _is_boolean = std::true_type;
 			using _is_value = std::true_type;
diff --git a/include/sqlpp11/floating_point.h b/include/sqlpp11/floating_point.h
index a43c4229..a5cdb5a2 100644
--- a/include/sqlpp11/floating_point.h
+++ b/include/sqlpp11/floating_point.h
@@ -41,6 +41,7 @@ namespace sqlpp
 		// floating_point value type
 		struct floating_point
 		{
+			using _value_type = floating_point;
 			using _base_value_type = floating_point;
 			using _is_numeric = std::true_type;
 			using _is_floating_point = std::true_type;
diff --git a/include/sqlpp11/integral.h b/include/sqlpp11/integral.h
index bb14761d..2e8ea407 100644
--- a/include/sqlpp11/integral.h
+++ b/include/sqlpp11/integral.h
@@ -42,8 +42,7 @@ namespace sqlpp
 		// integral value type
 		struct integral
 		{
-#warning why do I need base_value_type? Would it be sufficient to use _value_type instead?
-#warning what is the difference between _is_value and _is_expression?
+			using _value_type = integral;
 			using _base_value_type = integral;
 			using _is_numeric = std::true_type;
 			using _is_integral = std::true_type;
@@ -51,7 +50,6 @@ namespace sqlpp
 			using _is_expression = std::true_type;
 			using _cpp_value_type = int64_t;
 
-			using _value_type = integral;
 			
 			struct _parameter_t
 			{
diff --git a/include/sqlpp11/text.h b/include/sqlpp11/text.h
index 339d7dca..8a41fa24 100644
--- a/include/sqlpp11/text.h
+++ b/include/sqlpp11/text.h
@@ -41,6 +41,7 @@ namespace sqlpp
 		// text value type
 		struct text
 		{
+			using _value_type = text;
 			using _base_value_type = text;
 			using _is_text = std::true_type;
 			using _is_value = std::true_type;