diff --git a/rust/rust_test.go b/rust/rust_test.go
index 14bbd0b..81ad5ce 100644
--- a/rust/rust_test.go
+++ b/rust/rust_test.go
@@ -106,13 +106,14 @@
 // useMockedFs setup a default mocked filesystem for the test environment.
 func (tctx *testRustCtx) useMockedFs() {
 	tctx.fs = map[string][]byte{
-		"foo.rs":     nil,
-		"foo.c":      nil,
-		"src/bar.rs": nil,
-		"src/any.h":  nil,
-		"buf.proto":  nil,
-		"liby.so":    nil,
-		"libz.so":    nil,
+		"foo.rs":      nil,
+		"foo.c":       nil,
+		"src/bar.rs":  nil,
+		"src/any.h":   nil,
+		"proto.proto": nil,
+		"buf.proto":   nil,
+		"liby.so":     nil,
+		"libz.so":     nil,
 	}
 }