diff --git a/doc/v2/implicit.html b/doc/v2/implicit.html
index 10b4a82b..f3fda2d2 100644
--- a/doc/v2/implicit.html
+++ b/doc/v2/implicit.html
@@ -110,7 +110,7 @@ using namespace boost::python;
 struct X
 {
     X(int x) : v(x) {}
-    operator int() { return v; }
+    operator int() const { return v; }
     int v;
 };