diff --git a/book/ch10.rst b/book/ch10.rst
index f734f6c8..14e105a6 100644
--- a/book/ch10.rst
+++ b/book/ch10.rst
@@ -731,7 +731,7 @@ type-checker will try to infer as many types as possible, in this case
 it has not managed to fully specify the type of ``walk``,
 since its result type is unknown. Although we are intending ``walk``
 to receive type ``<e, t>``, as far as the type-checker knows, in this
-context it could be of some other type such as ``<e, e>`` or ``<e, <e, t>``. To help
+context it could be of some other type such as ``<e, e>`` or ``<e, <e, t>>``. To help
 the type-checker, we need to specify a `signature`:dt:, implemented as
 a dictionary that explicitly associates types with non-logical
 constants: