diff --git a/doc/spec/spec.tex b/doc/spec/spec.tex
index 2206e10e7b96e65b99b59b6efd529e28ea80e18a..34a0724a13ca47d9fd4542c101b73cd027b49924 100644
--- a/doc/spec/spec.tex
+++ b/doc/spec/spec.tex
@@ -14,6 +14,7 @@
 \usepackage{float}
 \usepackage[pdfpagemode=None,pdfstartview=FitH,pdfview=FitH,colorlinks=true]%
  {hyperref}
+\usepackage{utf8x}[inputenc]
 
 \newtheorem{theorem}{Theorem}[section]
 \newcommand{\idx}[1]{{\ensuremath{\mathit{#1}}}}