diff --git a/todoman/formatters.py b/todoman/formatters.py
index 9ba4c956..3e7d185e 100644
--- a/todoman/formatters.py
+++ b/todoman/formatters.py
@@ -85,13 +85,23 @@ def compact_multiple(self, todos):
 
         return tabulate(table, tablefmt='plain')
 
-    def _columnize(self, label, text):
+    def _columnize_text(self, label, text):
+        """Display text, split text by line-endings, on multiple colums,"""
+        """do nothing if text is empty or None"""
+        lines = text.splitlines() if text else None
+
+        return self._columnize_list(label, lines)
+
+    def _columnize_list(self, label, lst):
+        """Display list on multiple columns,"""
+        """do nothing if list is empty or None"""
+
         rows = []
 
-        lines = text.splitlines()
-        rows.append([label, lines[0]])
-        for line in lines[1:]:
-            rows.append([None, line])
+        if lst:
+            rows.append([label, lst[0]])
+            for line in lst[1:]:
+                rows.append([None, line])
 
         return rows
 
@@ -102,10 +112,8 @@ def detailed(self, todo):
         :param Todo todo: The todo component.
         """
         extra_rows = []
-        if todo.description:
-            extra_rows += self._columnize('Description', todo.description)
-        if todo.location:
-            extra_rows += self._columnize('Location', todo.location)
+        extra_rows += self._columnize_text('Description', todo.description)
+        extra_rows += self._columnize_text('Location', todo.location)
 
         if extra_rows:
             return '{}\n\n{}'.format(
diff --git a/todoman/model.py b/todoman/model.py
index 024dd582..10a71b40 100644
--- a/todoman/model.py
+++ b/todoman/model.py
@@ -160,19 +160,44 @@ def clone(self):
     )
 
     def __setattr__(self, name, value):
-        # Avoids accidentally setting a field to None when that's not a valid
-        # attribute.
-        if not value:
-            if name in Todo.RRULE_FIELDS:
-                return object.__setattr__(self, name, '')
-            if name in Todo.STRING_FIELDS:
-                return object.__setattr__(self, name, '')
-            if name in Todo.INT_FIELDS:
-                return object.__setattr__(self, name, 0)
-            if name in Todo.LIST_FIELDS:
-                return object.__setattr__(self, name, [])
-
-        return object.__setattr__(self, name, value)
+        """Check type and avoid setting fields to None"""
+        """when that is not a valid attribue."""
+
+        v = value
+
+        if name in Todo.RRULE_FIELDS:
+            if value is None:
+                v = ''
+            else:
+                assert isinstance(value, str), (
+                       "Got {0} for {1} where str was expected"
+                       .format(type(value), name))
+
+        if name in Todo.STRING_FIELDS:
+            if value is None:
+                v = ''
+            else:
+                assert isinstance(value, str), (
+                       "Got {0} for {1} where str was expected"
+                       .format(type(value), name))
+
+        if name in Todo.INT_FIELDS:
+            if value is None:
+                v = 0
+            else:
+                assert isinstance(value, int), (
+                       "Got {0} for {1} where int was expected"
+                       .format(type(value), name))
+
+        if name in Todo.LIST_FIELDS:
+            if value is None:
+                v = []
+            else:
+                assert isinstance(value, list), (
+                       "Got {0} for {1} where list was expected"
+                       .format(type(value), name))
+
+        return object.__setattr__(self, name, v)
 
     @property
     def is_completed(self):