diff --git a/source/utilities.tex b/source/utilities.tex
index 0a26e0266a..ea806496b4 100644
--- a/source/utilities.tex
+++ b/source/utilities.tex
@@ -4450,7 +4450,7 @@
 \begin{codeblock}
 namespace std {
   template<class T>
-  class optional<T&> {
+    class optional<T&> {
     public:
       using value_type     = T;
       using iterator       = @\impdefnc@;            // see~\ref{optional.ref.iterators}