diff --git a/eval/eval.go b/eval/eval.go
index 62178c2..7a8dc05 100644
--- a/eval/eval.go
+++ b/eval/eval.go
@@ -58,7 +58,7 @@ func (this *evaluator) evaluateConstant (expression entity.Expression) (entity.E
 		return nil, errors.Errorf (
 			expression.Position(),
 			"%v expressions are currently unsupported by the " +
-			"constant expression evaluator")
+			"constant expression evaluator", expression.Description())
 	}
 }