diff --git a/strings.Rmd b/strings.Rmd
index 033316d..9a424dc 100644
--- a/strings.Rmd
+++ b/strings.Rmd
@@ -519,7 +519,7 @@ r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\]
 ?:\r\n)?[ \t])*))*)?;\s*)
 ```
 
-This is a somewhat pathological example (because email addresses are actually suprisingly complex), but is used in real code. See the stackoverflow discussion at <http://stackoverflow.com/a/201378> for more details. 
+This is a somewhat pathological example (because email addresses are actually surprisingly complex), but is used in real code. See the stackoverflow discussion at <http://stackoverflow.com/a/201378> for more details. 
 
 Don't forget that you're in a programming language and you have other tools at your disposal. Instead of creating one complex regular expression, it's often easier to write a series of simpler regexps. If you get stuck trying to create a single regexp that solves your problem, take a step back and think if you could break the problem down into smaller pieces, solving each challenge before moving onto the next one.