diff --git a/src/calibre/ebooks/chm/reader.py b/src/calibre/ebooks/chm/reader.py
index 3e5c0d24d9..6801254636 100644
--- a/src/calibre/ebooks/chm/reader.py
+++ b/src/calibre/ebooks/chm/reader.py
@@ -53,6 +53,7 @@ class CHMReader(CHMFile):
         self._playorder = 0
         self._metadata = False
         self._extracted = False
+        self.re_encoded_files = set()
 
         # location of '.hhc' file, which is the CHM TOC.
         if self.topics is None:
@@ -147,8 +148,8 @@ class CHMReader(CHMFile):
                 f.write(data)
 
         self._extracted = True
-        files = [x for x in os.listdir(output_dir) if
-                os.path.isfile(os.path.join(output_dir, x))]
+        files = [y for y in os.listdir(output_dir) if
+                os.path.isfile(os.path.join(output_dir, y))]
         if self.hhc_path not in files:
             for f in files:
                 if f.lower() == self.hhc_path.lower():
@@ -249,7 +250,9 @@ class CHMReader(CHMFile):
             pass
         # do not prettify, it would reformat the <pre> tags!
         try:
-            return str(soup)
+            ans = str(soup)
+            self.re_encoded_files.add(os.path.abspath(htmlpath))
+            return ans
         except RuntimeError:
             return data
 
diff --git a/src/calibre/ebooks/conversion/plugins/chm_input.py b/src/calibre/ebooks/conversion/plugins/chm_input.py
index a846682432..473398e1bc 100644
--- a/src/calibre/ebooks/conversion/plugins/chm_input.py
+++ b/src/calibre/ebooks/conversion/plugins/chm_input.py
@@ -25,7 +25,6 @@ class CHMInput(InputFormatPlugin):
         self._chm_reader = rdr
         return rdr.hhc_path
 
-
     def convert(self, stream, options, file_ext, log, accelerators):
         from calibre.ebooks.chm.metadata import get_metadata_from_reader
         from calibre.customize.ui import plugin_for_input_format
@@ -63,7 +62,10 @@ class CHMInput(InputFormatPlugin):
 
             options.debug_pipeline = None
             options.input_encoding = 'utf-8'
-            htmlpath, toc = self._create_html_root(mainpath, log, encoding)
+            uenc = encoding
+            if os.path.abspath(mainpath) in self._chm_reader.re_encoded_files:
+                uenc = 'utf-8'
+            htmlpath, toc = self._create_html_root(mainpath, log, uenc)
             oeb = self._create_oebbook_html(htmlpath, tdir, options, log, metadata)
             options.debug_pipeline = odi
             if toc.count() > 1: