diff --git a/configure.in b/configure.in
index eebb2aa..1750a19 100644
--- a/configure.in
+++ b/configure.in
@@ -129,27 +129,8 @@ AC_SUBST(HTML_DIR)
 
 AC_CHECK_PROG(GTKDOC, gtkdoc-mkdb, true, false)
 
-gtk_doc_min_version=0.9
 if $GTKDOC ; then 
-    gtk_doc_version=`gtkdoc-mkdb --version`
-    AC_MSG_CHECKING([gtk-doc version ($gtk_doc_version) >= $gtk_doc_min_version])
-
-    IFS="${IFS= 	}"; gtk_save_IFS="$IFS"; IFS="."
-    set $gtk_doc_version
-    for min in $gtk_doc_min_version ; do
-        cur=$1; shift
-        if test -z $min ; then break; fi
-        if test -z $cur ; then GTKDOC=false; break; fi
-        if test $cur -gt $min ; then break ; fi
-        if test $cur -lt $min ; then GTKDOC=false; break ; fi
-    done
-    IFS="$gtk_save_IFS"
-
-    if $GTKDOC ; then
-      AC_MSG_RESULT(yes)
-   else
-      AC_MSG_RESULT(no)
-   fi
+GTK_DOC_CHECK([0.9])
 fi
 
 AC_CHECK_PROG(DB2HTML, db2html, true, false)
diff --git a/dic/Makefile.am b/dic/Makefile.am
index a74dbf1..f2ec141 100644
--- a/dic/Makefile.am
+++ b/dic/Makefile.am
@@ -1,7 +1,7 @@
 DICTS=bg.xml ca.xml cs.xml cy.xml da.xml de.xml el.xml en.xml eo.xml es.xml \
       et.xml eu.xml fi.xml fr.xml ga.xml gl.xml he.xml hu.xml ia.xml id.xml \
       is.xml it.xml lv.xml mi.xml ms.xml mt.xml nl.xml nn.xml pl.xml pt.xml \
-      ro.xml ru.xml sv.xml tl.xml tr.xml uk.xml yi.xml en.xml
+      ro.xml ru.xml sv.xml tl.xml tr.xml uk.xml yi.xml
 
 pkgdata_DATA = $(DICTS)
 
diff --git a/doc/ots-docs.sgml b/doc/ots-docs.sgml
index 199983e..e9a64e5 100644
--- a/doc/ots-docs.sgml
+++ b/doc/ots-docs.sgml
@@ -1,11 +1,13 @@
-<!doctype book PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
-	<!notation PNG system "PNG">
-	<!entity % local.notation.class "| PNG">
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V4.1.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"
+[
+	<!NOTATION PNG SYSTEM "PNG">
+	<!ENTITY % local.notation.class "| PNG">
 
-	<!entity hash "#">
-	<!entity percent "%">
-	<!entity ObjectIndex	SYSTEM "sgml/object_index.sgml">
-	<!entity TreeIndex	SYSTEM "sgml/tree_index.sgml">
+	<!ENTITY hash "#">
+	<!-- !ENTITY percent "%" -->
+	<!ENTITY ObjectIndex	SYSTEM "sgml/object_index.sgml">
+	<!ENTITY TreeIndex	SYSTEM "sgml/tree_index.sgml">
 ]>
 
 <book id="index">
diff --git a/src/Makefile.am b/src/Makefile.am
index 504c3d2..5349897 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -43,7 +43,7 @@ libots_1_include_HEADERS = 	\
 	libots.h
 
 bin_PROGRAMS=ots
-ldadd = $(top_builddir)/src/libots-1.la $(OTS_LIBS) $(POPT_LIBS)
+ldadd = libots-1.la $(OTS_LIBS) $(POPT_LIBS)
 
 ots_LDADD=$(ldadd)
 
diff --git a/src/grader-tf.c b/src/grader-tf.c
index d05b19c..0de4687 100644
--- a/src/grader-tf.c
+++ b/src/grader-tf.c
@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 #include "libots.h"
 
 /*Grader - using the Term frequency algorithm. Will give each line a score*/