diff --git a/source/uax31.tex b/source/uax31.tex
index 6a13e10464..6574a48637 100644
--- a/source/uax31.tex
+++ b/source/uax31.tex
@@ -32,8 +32,8 @@
 \tcode{<Continue>} has the XID_Continue property, and
 \tcode{<Medial>} is a list of characters permitted between continue characters.
 \UAX{31} also specifies some standard profiles,
-including the Mathematical Compatability Notation profile.
-For \Cpp{} we apply the Mathematical Compatability Notation profile,
+including the Mathematical Compatibility Notation profile.
+For \Cpp{} we apply the Mathematical Compatibility Notation profile,
 and we add the character \unicode{005f}{low line}, or \tcode{_},
 to the set of permitted \tcode{<Start>} characters.
 The \tcode{<Medial>} set is empty.