diff --git a/source/numerics.tex b/source/numerics.tex
index 61c871082f..f8c2129508 100644
--- a/source/numerics.tex
+++ b/source/numerics.tex
@@ -10479,6 +10479,7 @@
 
 \rSec2[linalg.syn]{Header \tcode{<linalg>} synopsis}
 
+\indexheader{linalg}%
 \begin{codeblock}
 namespace std::linalg {
   // \ref{linalg.tags.order}, storage order tags