diff --git a/libqpdf/QPDF_optimization.cc b/libqpdf/QPDF_optimization.cc
index 1a7bac11..17ea0066 100644
--- a/libqpdf/QPDF_optimization.cc
+++ b/libqpdf/QPDF_optimization.cc
@@ -1,4 +1,4 @@
-// See doc/optimization.
+// See "Optimization" sectino of manual.
 
 #include <qpdf/QPDF.hh>