diff --git a/lib/domain/libimaghabit/src/util.rs b/lib/domain/libimaghabit/src/util.rs
index 80254471..3d60cc58 100644
--- a/lib/domain/libimaghabit/src/util.rs
+++ b/lib/domain/libimaghabit/src/util.rs
@@ -17,9 +17,14 @@
 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 //
 
+use std::ops::BitXor;
+
 use chrono::NaiveDate;
 use error::Result;
 
+use habit::HabitTemplate;
+use instance::HabitInstance;
+
 pub const NAIVE_DATE_STRING_FORMAT : &'static str = "%Y-%m-%d";
 
 pub fn date_to_string(ndt: &NaiveDate) -> String {
@@ -30,3 +35,18 @@ pub fn date_from_string(s: &str) -> Result<NaiveDate> {
     NaiveDate::parse_from_str(s, NAIVE_DATE_STRING_FORMAT).map_err(From::from)
 }
 
+/// Helper trait to check whether a object which can be a habit instance and a habit template is
+/// actually a valid object, whereas "valid" is defined that it is _either_ an instance or a
+/// template (think XOR).
+pub trait IsValidHabitObj : HabitInstance + HabitTemplate {
+    fn is_valid_havit_obj(&self) -> Result<bool> {
+        self.is_habit_instance().and_then(|b| self.is_habit_template().map(|a| a.bitxor(b)))
+    }
+}
+
+impl<H> IsValidHabitObj for H
+    where H: HabitInstance + HabitTemplate
+{
+    // Empty
+}
+