diff --git a/source/ch05-discovery/main.ptx b/source/ch05-discovery/main.ptx
index 1942271..fb6cd0f 100644
--- a/source/ch05-discovery/main.ptx
+++ b/source/ch05-discovery/main.ptx
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
 <chapter xml:id="ch-chapter-discovery" xmlns:xi="http://www.w3.org/2001/XInclude">
-  <title>Discovering New Mah</title>
+  <title>Discovering New Math</title>
 
   <introduction>
     <p> Text before the first section. </p>