diff --git a/HISTORY.rst b/HISTORY.rst
index 49665fc898..1fefb4ece6 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -22,6 +22,8 @@
 * Add separate Python 2 and Python 3 versions of the 
   MetadataType model .comma_splitter() static method.
 * Update the metadata app tests to work on Python 3.
+* Make sure metadata lookup choices are a list to be able to add the
+  optional marker (Python 3). 
 
 3.1.4 (2018-10-4)
 =================
diff --git a/mayan/apps/metadata/forms.py b/mayan/apps/metadata/forms.py
index 83153abaae..9c6c2663dc 100644
--- a/mayan/apps/metadata/forms.py
+++ b/mayan/apps/metadata/forms.py
@@ -62,7 +62,7 @@ class DocumentMetadataForm(forms.Form):
                         label=self.fields['value'].label
                     )
                     choices = self.metadata_type.get_lookup_values()
-                    choices = zip(choices, choices)
+                    choices = list(zip(choices, choices))
                     if not required:
                         choices.insert(0, ('', '------'))
                     self.fields['value'].choices = choices