In a text, I get an overfull hbox. To avoid this, I define an optional hyphenation point:

bla bla bla un\-known bla bla bla

pdflatex indeed hyphenates the word at that point. But when I declare the optional hyphenation point in the preamble like this


then pdflatex will NOT hyphenate there. The reason seems to be that LaTeX still thinks that the typeset text does not look good enough with the line break after 'un-'. But then why is the behavior different for the inline optional hyphenation to the optional hyphenation declared in the preamble?

  • Are you using multiple languages with babel?
    – egreg
    Apr 7, 2012 at 15:45
  • 1
    If you can process your document with LuaTeX: include the package lua-visual-debug and you'll see the possible hyphenation points.
    – topskip
    Apr 7, 2012 at 16:07

1 Answer 1


Try adding \showthe\lefthyphenmin so TeX stops and shows the value of this parameter. If it is set more than 2 then automatic hyphenation will never break after 2 letters. The default (for English) is 2, but some language setups change this.

  • No babel package used; but \showthe\lefthyphemin did the trick. It was set to 3. After setting it to 2 (simply use \lefthyphenmin=2), my optional hyphenation work as expected. Thanks for the hint.
    – Klaus
    Apr 9, 2012 at 12:19

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