diff --git a/helpers/pygments.go b/helpers/pygments.go
index 11b0f23d4..3f0f90b7a 100644
--- a/helpers/pygments.go
+++ b/helpers/pygments.go
@@ -122,6 +122,7 @@ func init() {
 	pygmentsKeywords["noclasses"] = true
 	pygmentsKeywords["hl_lines"] = true
 	pygmentsKeywords["linenos"] = true
+	pygmentsKeywords["classprefix"] = true
 }
 
 func parsePygmentsOpts(in string) (string, error) {