diff --git a/math/computational_geometry/notes.page b/math/computational_geometry/notes.page
index 881a0ce..df8b82b 100644
--- a/math/computational_geometry/notes.page
+++ b/math/computational_geometry/notes.page
@@ -30,5 +30,5 @@ two parts.  In particular, the two components of $\Bbb{R}^2\setminus
 A point $x$ is *interior* if a ray through it in a fixed direction not
 parallel to an edge passes through an odd number of edges.
 
-A point $x$ is *exterior$ if a ray through it ... etc ... through an
+A point $x$ is *exterior* if a ray through it ... etc ... through an
 even number of edges.