diff --git a/tryton/gui/window/view_form/model/field.py b/tryton/gui/window/view_form/model/field.py
index 26633da93e..548ac79ccc 100644
--- a/tryton/gui/window/view_form/model/field.py
+++ b/tryton/gui/window/view_form/model/field.py
@@ -779,7 +779,7 @@ class ReferenceField(CharField):
     def get(self, record):
         if (record.value.get(self.name)
                 and record.value[self.name][0]
-                and record.value[self.name][1] >= 0):
+                and record.value[self.name][1] >= -1):
             return ','.join(map(str, record.value[self.name]))
         return None