diff --git a/src/signals/path-matchers.ts b/src/signals/path-matchers.ts
index e03567221e..3f5a2e69f8 100644
--- a/src/signals/path-matchers.ts
+++ b/src/signals/path-matchers.ts
@@ -51,9 +51,10 @@ function isGeneratedFileFrom(parts: NormalizedPath): boolean {
     /(^|\/)(__generated__|generated)\//.test(norm) ||
     /\.(generated|gen)\.[^/]+$/.test(norm) ||
     // protoc output: Go/TS/JS plugins emit `.pb.{go,ts,js}`, the reference C++ plugin emits
-    // `.pb.cc` / `.pb.h`, the Swift plugin emits `.pb.swift`, and the Dart plugin emits
-    // `.pb.dart` (the `.pb` infix keeps hand-written `.dart`/`.kt` from matching).
-    /\.pb\.(go|ts|js|cc|h|swift|dart|kt)$/.test(norm) ||
+    // `.pb.cc` / `.pb.h`, the Swift plugin emits `.pb.swift`, the Dart plugin emits `.pb.dart`,
+    // the Kotlin plugin emits `.pb.kt`, and the C# plugin emits `.pb.cs`.
+    // `.pb.dart`/`.pb.kt`/`.pb.cs` (the `.pb` infix keeps hand-written sources from matching).
+    /\.pb\.(go|ts|js|cc|h|swift|dart|kt|cs)$/.test(norm) ||
     // Python protobuf: message stubs are `*_pb2.py[i]`; the gRPC plugin emits sibling
     // `*_pb2_grpc.py[i]` service stubs, which are the same machine-generated output.
     /_pb2(_grpc)?\.pyi?$/.test(norm) ||
diff --git a/test/unit/path-matchers.test.ts b/test/unit/path-matchers.test.ts
index cac5f2dd79..f363acd404 100644
--- a/test/unit/path-matchers.test.ts
+++ b/test/unit/path-matchers.test.ts
@@ -78,6 +78,7 @@ describe("isGeneratedFile", () => {
       "proto/messages.pb.swift",
       "proto/messages.pb.dart",
       "proto/messages.pb.kt",
+      "proto/messages.pb.cs",
       "lib/user.freezed.dart",
       "lib/api_client.gr.dart",
       "ui/MainForm.Designer.cs",