diff --git a/src/calibre/gui2/preferences/coloring.py b/src/calibre/gui2/preferences/coloring.py
index ca30563703..defadf71c7 100644
--- a/src/calibre/gui2/preferences/coloring.py
+++ b/src/calibre/gui2/preferences/coloring.py
@@ -836,6 +836,10 @@ class RulesModel(QAbstractListModel):  # {{{
                 else:
                     continue
                 break
+        if action_name == Rule.INVALID_CONDITION:
+            return (
+                _('<li>The condition using column <b>%(col)s</b> is <b>invalid</b>')
+                % dict(col=c))
         return (
             _('<li>If the <b>%(col)s</b> column <b>%(action)s</b> value: <b>%(val)s</b>') % dict(
                 col=c, action=action_name, val=prepare_string_for_xml(v)))
diff --git a/src/calibre/library/coloring.py b/src/calibre/library/coloring.py
index ab8551b0d7..ef48508233 100644
--- a/src/calibre/library/coloring.py
+++ b/src/calibre/library/coloring.py
@@ -17,6 +17,8 @@ class Rule(object):  # {{{
 
     SIGNATURE = '# BasicColorRule():'
 
+    INVALID_CONDITION = _('INVALID CONDITION')
+
     def __init__(self, fm, color=None):
         self.color = color
         self.fm = fm
@@ -28,6 +30,8 @@ class Rule(object):  # {{{
         v = self.validate_condition(col, action, val)
         if v:
             raise ValueError(v)
+        if self.apply_condition((col, action, val)) is None:
+            action = self.INVALID_CONDITION
         self.conditions.append((col, action, val))
 
     def validate_condition(self, col, action, val):