diff --git a/src/calibre/gui2/custom_column_widgets.py b/src/calibre/gui2/custom_column_widgets.py
index 4223a638f2..5cbd318ee9 100644
--- a/src/calibre/gui2/custom_column_widgets.py
+++ b/src/calibre/gui2/custom_column_widgets.py
@@ -234,9 +234,12 @@ class Comments(Base):
         self.widgets = [self._box]
 
     def setter(self, val):
-        if val is None:
+        if not val or not val.strip():
             val = ''
-        self._tb.html = comments_to_html(val)
+        else:
+            val = comments_to_html(val)
+        self._tb.html = val
+        self._tb.wyswyg_dirtied()
 
     def getter(self):
         val = unicode(self._tb.html).strip()