diff --git a/python/adjoint/objective.py b/python/adjoint/objective.py
index 9789d94b8..cd7d143d4 100644
--- a/python/adjoint/objective.py
+++ b/python/adjoint/objective.py
@@ -44,7 +44,7 @@ def place_adjoint_source(self, dJ):
 
     def get_evaluation(self):
         """Evaluates the objective quantity."""
-        if self._eval:
+        if self._eval is not None:
             return self._eval
         else:
             raise RuntimeError(