diff --git a/pep-3137.txt b/pep-3137.txt
index 9c3cc3a58..fb14b9bae 100644
--- a/pep-3137.txt
+++ b/pep-3137.txt
@@ -190,7 +190,7 @@ except where mentioned:
     the return type is that of the first argument (this seems arbitrary
     until you consider how ``+=`` works).
 
-  - ``b1 += b2'': mutates b1 if it is a buffer object.
+  - ``b1 += b2``: mutates b1 if it is a buffer object.
 
   - ``b * n``, ``n * b``: repetition; n must be an integer.