diff --git a/doc/design-paper/challenges.tex b/doc/design-paper/challenges.tex
index ceb77530c8..6949693bf0 100644
--- a/doc/design-paper/challenges.tex
+++ b/doc/design-paper/challenges.tex
@@ -159,7 +159,7 @@ Most node operators do not want to allow arbitrary TCP traffic. % to leave
 To address this, Tor provides \emph{exit policies} so
 each exit node can block the IP addresses and ports it is unwilling to allow.
 Tor nodes advertise their exit policies to the directory servers, so that
-client can tell which nodes will support their connections.
+clients can tell which nodes will support their connections.
 
 As of January 2005, the Tor network has grown to around a hundred nodes
 on four continents, with a total capacity exceeding 1Gbit/s. Appendix A
@@ -1102,7 +1102,7 @@ new nodes with those ASes in mind?
 Citizens in a variety of countries, such as most recently China and
 Iran, are blocked from accessing various sites outside
 their country. These users try to find any tools available to allow
-them to get-around these firewalls. Some anonymity networks, such as
+them to get around these firewalls. Some anonymity networks, such as
 Six-Four~\cite{six-four}, are designed specifically with this goal in
 mind; others like the Anonymizer~\cite{anonymizer} are paid by sponsors
 such as Voice of America to encourage Internet
@@ -1284,7 +1284,7 @@ choice of threat model and requirements.  If we did not need to increase
 network capacity to support more users, we could simply
  adopt even stricter validation requirements, and reduce the number of
 nodes in the network to a trusted minimum.  
-But, we can only do that if can simultaneously make node capacity
+But, we can only do that if we can simultaneously make node capacity
 scale much more than we anticipate to be feasible soon, and if we can find
 entities willing to run such nodes, an equally daunting prospect.