diff --git a/test/dump_text_file.cxx b/test/dump_text_file.cxx
index 20af5678f..92ac64a12 100644
--- a/test/dump_text_file.cxx
+++ b/test/dump_text_file.cxx
@@ -51,17 +51,14 @@ dump_input_stream(InputStreamPtr &&is)
 		dump_text_file(tis);
 	}
 
-	is->Lock();
+	const ScopeLock protect(is->mutex);
 
 	Error error;
 	if (!is->Check(error)) {
 		LogError(error);
-		is->Unlock();
 		return EXIT_FAILURE;
 	}
 
-	is->Unlock();
-
 	return 0;
 }
 
diff --git a/test/run_input.cxx b/test/run_input.cxx
index 4433611f8..757895124 100644
--- a/test/run_input.cxx
+++ b/test/run_input.cxx
@@ -49,7 +49,7 @@ tag_save(FILE *file, const Tag &tag)
 static int
 dump_input_stream(InputStream *is)
 {
-	is->Lock();
+	const ScopeLock protect(is->mutex);
 
 	/* print meta data */
 
@@ -84,12 +84,9 @@ dump_input_stream(InputStream *is)
 	Error error;
 	if (!is->Check(error)) {
 		LogError(error);
-		is->Unlock();
 		return EXIT_FAILURE;
 	}
 
-	is->Unlock();
-
 	return 0;
 }