diff --git a/src/calibre/ebooks/markdown/markdown.py b/src/calibre/ebooks/markdown/markdown.py
index caadce2924..46ac21983c 100644
--- a/src/calibre/ebooks/markdown/markdown.py
+++ b/src/calibre/ebooks/markdown/markdown.py
@@ -65,7 +65,8 @@ Constants you might want to modify
 COMMAND_LINE_LOGGING_LEVEL = CRITICAL
 TAB_LENGTH = 4               # expand tabs to this many spaces
 ENABLE_ATTRIBUTES = True     # @id = xyz -> <... id="xyz">
-SMART_EMPHASIS = True        # this_or_that does not become this<i>or</i>that
+#SMART_EMPHASIS = True        # this_or_that does not become this<i>or</i>that
+SMART_EMPHASIS = False      # this_or_that needs to have _ escaped as \_.
 DEFAULT_OUTPUT_FORMAT = 'xhtml1'     # xhtml or html4 output
 HTML_REMOVED_TEXT = "[HTML_REMOVED]" # text used instead of HTML in safe mode
 BLOCK_LEVEL_ELEMENTS = re.compile("p|div|h[1-6]|blockquote|pre|table|dl|ol|ul"