diff --git a/doc/subgraph.html b/doc/subgraph.html
index 4150a38d..811e8c94 100644
--- a/doc/subgraph.html
+++ b/doc/subgraph.html
@@ -91,7 +91,7 @@ their parent.
 
 <pre>
 Graph& G1 = G0.create_subgraph(), G2 = G0.create_subgraph();
-enum { A1, B1, C2 }; // for conveniently referring to vertices in G1
+enum { A1, B1, C1 }; // for conveniently referring to vertices in G1
 enum { A2, B2 };     // for conveniently referring to vertices in G2
 </pre>