diff --git a/src/calibre/ebooks/conversion/preprocess.py b/src/calibre/ebooks/conversion/preprocess.py
index 029b9752e1..1aae939a06 100644
--- a/src/calibre/ebooks/conversion/preprocess.py
+++ b/src/calibre/ebooks/conversion/preprocess.py
@@ -237,14 +237,14 @@ class HTMLPreProcessor(object):
                 (re.compile(getattr(self.extra_opts, 'footer_regex')), lambda match : '')
             )
 
-            end_rules = []
-            if getattr(self.extra_opts, 'unwrap_factor', None):
-                length = line_length(html, getattr(self.extra_opts, 'unwrap_factor'))
-                if length:
-                    end_rules.append(
-                        # Un wrap using punctuation
-                        (re.compile(r'(?<=.{%i}[a-z\.,;:)-IA])\s*(?P<ital></(i|b|u)>)?\s*(<p.*?>)\s*(?=(<(i|b|u)>)?\s*[\w\d(])' % length, re.UNICODE), wrap_lines),
-                    )
+        end_rules = []
+        if getattr(self.extra_opts, 'unwrap_factor', None):
+            length = line_length(html, getattr(self.extra_opts, 'unwrap_factor'))
+            if length:
+                end_rules.append(
+                    # Un wrap using punctuation
+                    (re.compile(r'(?<=.{%i}[a-z\.,;:)-IA])\s*(?P<ital></(i|b|u)>)?\s*(<p.*?>)\s*(?=(<(i|b|u)>)?\s*[\w\d(])' % length, re.UNICODE), wrap_lines),
+                )
 
         for rule in self.PREPROCESS + pre_rules + rules + end_rules:
             html = rule[0].sub(rule[1], html)
diff --git a/src/calibre/ebooks/oeb/transforms/structure.py b/src/calibre/ebooks/oeb/transforms/structure.py
index c377a8b3a8..b84222d82c 100644
--- a/src/calibre/ebooks/oeb/transforms/structure.py
+++ b/src/calibre/ebooks/oeb/transforms/structure.py
@@ -48,8 +48,10 @@ class DetectStructure(object):
 
         if opts.toc_filter is not None:
             regexp = re.compile(opts.toc_filter)
-            for node in self.oeb.toc.iter():
+            for node in list(self.oeb.toc.iter()):
                 if not node.title or regexp.search(node.title) is not None:
+                    self.log('Filtering', node.title if node.title else\
+                            'empty node', 'from TOC')
                     self.oeb.toc.remove(node)
 
         if opts.page_breaks_before is not None: