diff --git a/book/variables.md b/book/variables.md
index 5a88f269ed0..42bea23a52d 100644
--- a/book/variables.md
+++ b/book/variables.md
@@ -63,7 +63,8 @@ There are a couple of assignment operators used with mutable variables
 
 1. `+=`, `-=`, `*=` and `/=` are only valid in the contexts where their root operations are expected to work. For example, `+=` uses addition, so it can not be used for contexts where addition would normally fail
 2. `++=` requires that either the variable **or** the argument is a list.
-   :::
+
+:::
 
 #### More on Mutability