diff --git a/doc/tips/optimising_ikiwiki.mdwn b/doc/tips/optimising_ikiwiki.mdwn
index 0c67e606c..2999573ac 100644
--- a/doc/tips/optimising_ikiwiki.mdwn
+++ b/doc/tips/optimising_ikiwiki.mdwn
@@ -207,7 +207,7 @@ The best way to do it is:
 
 * Install [[!cpan Devel::NYTProf]]
 * `PERL5OPT=-d:NYTProf`
-* `export PER5OPT`
+* `export PERL5OPT`
 * Now run ikiwiki as usual, and it will generate a `nytprof.out` file.
 * Run `nytprofhtml` to generate html files.
 * Those can be examined to see what parts of ikiwiki are being slow.