doc/refman.tex | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/refman.tex b/doc/refman.tex
index b384e97..be88fde 100644
--- a/doc/refman.tex
+++ b/doc/refman.tex
@@ -1,3 +1,4 @@
+\RequirePackage{ifpdf}
 \documentclass[11pt,twoside,a4paper]{book}
 
 %----------------------------------------------------------------------