diff --git a/src/calibre/ebooks/txt/processor.py b/src/calibre/ebooks/txt/processor.py
index be017b3f4f..65a97dba4d 100644
--- a/src/calibre/ebooks/txt/processor.py
+++ b/src/calibre/ebooks/txt/processor.py
@@ -220,7 +220,7 @@ def remove_indents(txt):
     '''
     Remove whitespace at the beginning of each line.
     '''
-    return '\n'.join(l.lstrip() for l in txt.splitlines())
+    return re.sub(r'^\s+', '', txt, flags=re.MULTILINE)
 
 
 def opf_writer(path, opf_name, manifest, spine, mi):