diff --git a/ttcn3/types/types.go b/ttcn3/types/types.go
index 2ffbbbc9..02437cb6 100644
--- a/ttcn3/types/types.go
+++ b/ttcn3/types/types.go
@@ -146,7 +146,15 @@ type PrimitiveType struct {
 }
 
 func (t *PrimitiveType) String() string {
-	return ""
+	if t.ValueConstraints == nil {
+		return t.Kind.String()
+	}
+	var constraints []string
+	for _, v := range t.ValueConstraints {
+		constraints = append(constraints, v.String())
+	}
+	return fmt.Sprintf("%s (%s)", t.Kind.String(), strings.Join(constraints, ", "))
+
 }
 
 // A ListType represents a collection of values of the same type, such as a
diff --git a/ttcn3/types/types_test.go b/ttcn3/types/types_test.go
index 350c5876..52c04553 100644
--- a/ttcn3/types/types_test.go
+++ b/ttcn3/types/types_test.go
@@ -37,30 +37,30 @@ func TestTypeStrings(t *testing.T) {
 
 		// Predefined types
 
-		{skip: true, Output: "any", Type: types.Predefined["any"]},
+		{Output: "any", Type: types.Predefined["any"]},
 		{skip: true, Output: "anytype", Type: types.Predefined["anytype"]},
 		{skip: true, Output: "bitstring", Type: types.Predefined["bitstring"]},
-		{skip: true, Output: "boolean", Type: types.Predefined["boolean"]},
+		{Output: "boolean", Type: types.Predefined["boolean"]},
 		{skip: true, Output: "charstring", Type: types.Predefined["charstring"]},
 		{skip: true, Output: "default", Type: types.Predefined["default"]},
-		{skip: true, Output: "float", Type: types.Predefined["float"]},
+		{Output: "float", Type: types.Predefined["float"]},
 		{skip: true, Output: "hexstring", Type: types.Predefined["hexstring"]},
-		{skip: true, Output: "integer", Type: types.Predefined["integer"]},
+		{Output: "integer", Type: types.Predefined["integer"]},
 		{skip: true, Output: "octetstring", Type: types.Predefined["octetstring"]},
 		{skip: true, Output: "timer", Type: types.Predefined["timer"]},
 		{skip: true, Output: "universal charstring", Type: types.Predefined["universal charstring"]},
 
 		// Primitive types
 
-		{skip: true, Output: "any",
+		{Output: "any",
 			Type: &types.PrimitiveType{}},
 
-		{skip: true, Output: "any ()",
+		{Output: "any ()",
 			Type: &types.PrimitiveType{
 				ValueConstraints: []types.Value{},
 			}},
 
-		{skip: true, Output: "any (5, 1..10)",
+		{Output: "any (5, 1..10)",
 			Type: &types.PrimitiveType{
 				ValueConstraints: []types.Value{
 					{Expr: intVal},
@@ -68,12 +68,12 @@ func TestTypeStrings(t *testing.T) {
 				},
 			}},
 
-		{skip: true, Output: "integer",
+		{Output: "integer",
 			Type: &types.PrimitiveType{
 				Kind: types.Integer,
 			}},
 
-		{skip: true, Output: "integer (1)",
+		{Output: "integer (5)",
 			Type: &types.PrimitiveType{
 				Kind:             types.Integer,
 				ValueConstraints: []types.Value{{Expr: intVal}},