diff --git a/GTSAM-Concepts.md b/GTSAM-Concepts.md
index 7858e8390..3d425a4df 100644
--- a/GTSAM-Concepts.md
+++ b/GTSAM-Concepts.md
@@ -294,6 +294,7 @@ Boost provides a nice way to check whether a given type satisfies a concept. For
 Using the following from Mike Bosse's prototype:
 
 ```
+#!c++
 template<class C>
 struct ChartConcept {