diff --git a/src/calibre/ebooks/txt/processor.py b/src/calibre/ebooks/txt/processor.py
index a12e8a0761..dac1e34df7 100644
--- a/src/calibre/ebooks/txt/processor.py
+++ b/src/calibre/ebooks/txt/processor.py
@@ -77,7 +77,7 @@ def separate_paragraphs_print_formatted(txt):
 
 def preserve_spaces(txt):
     txt = txt.replace(' ', ' ')
-    txt = txt.replace('\t', '	')
+    txt = txt.replace('\t', '    ')
     return txt
 
 def opf_writer(path, opf_name, manifest, spine, mi):