diff --git a/pdf/grandpa.tex b/pdf/grandpa.tex
index bf78b61..1c60489 100644
--- a/pdf/grandpa.tex
+++ b/pdf/grandpa.tex
@@ -5,10 +5,19 @@
 \usepackage{amsthm}
 \usepackage{fullpage}
 
-\usepackage[bookmarks=true, unicode=true, pdftitle={GRANDPA: a blockchain finality gadget}, pdfauthor={Alistair Stewart},pdfkeywords={Polkadot, blockchain finality gadget},pdfborder={0 0 0.5 [1 3]}]{hyperref}
+\usepackage[bookmarks=true, unicode=true, pdftitle={GRANDPA: a blockchain finality gadget}, pdfauthor={Alistair Stewart},pdfkeywords={blockchain finality gadget, consensus, Polkadot, Substrate},pdfborder={0 0 0.5 [1 3]}]{hyperref}
 \usepackage{url}
 \usepackage[numbers]{natbib}
 
+
+\usepackage{tabu} %requires array.
+
+%This should be the last package before \input{Version.tex}
+\PassOptionsToPackage{hyphens}{url}\usepackage{hyperref}
+% "hyperref loads the url package internally. Use \PassOptionsToPackage{hyphens}{url}\usepackage{hyperref} to pass the option to the url package when it is loaded by hyperref. This avoids any package option clashes." Source: <https://tex.stackexchange.com/questions/3033/forcing-linebreaks-in-url/3034#comment44478_3034>.
+% Note also this: "If the \PassOptionsToPackage{hyphens}{url} approach does not work, maybe it's "because you're trying to load the url package with a specific option, but it's being loaded by one of your packages before that with a different set of options. Try loading the url package earlier than the package that requires it. If it's loaded by the document class, try using \RequirePackage[hyphens]{url} before the document class." Source: <https://tex.stackexchange.com/questions/3033/forcing-linebreaks-in-url/3034#comment555944_3034>.
+% For more information on using the hyperref package, refer to e.g. https://en.wikibooks.org/w/index.php?title=LaTeX/Hyperlinks&stable=0#Hyperlink_and_Hypertarget.
+
 \bibliographystyle{plainnat}
 
 \newtheorem{theorem}{Theorem}[section]