diff --git a/runtime/plugins/comment/comment.lua b/runtime/plugins/comment/comment.lua
index ccda2e1297..3ba68a300e 100644
--- a/runtime/plugins/comment/comment.lua
+++ b/runtime/plugins/comment/comment.lua
@@ -11,6 +11,7 @@ ft["apacheconf"] = "# %s"
 ft["batch"] = ":: %s"
 ft["c"] = "// %s"
 ft["c++"] = "// %s"
+ft["csharp"] = "// %s"
 ft["cmake"] = "# %s"
 ft["conf"] = "# %s"
 ft["crystal"] = "# %s"