diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 408c074..59494f7 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -59,8 +59,8 @@ target_link_libraries(file_upload_client ${EXAMPLE_LIBS})
 add_executable(file_upload_server file_upload_server.cc)
 target_link_libraries(file_upload_server ${EXAMPLE_LIBS})
 
-add_executable(static_server static_server.cc)
-target_link_libraries(static_server ${EXAMPLE_LIBS})
+add_executable(file_server file_server.cc)
+target_link_libraries(file_server ${EXAMPLE_LIBS})
 
 add_executable(server_states server_states.cc)
 target_link_libraries(server_states ${EXAMPLE_LIBS})
diff --git a/examples/static_server.cc b/examples/file_server.cc
similarity index 58%
rename from examples/static_server.cc
rename to examples/file_server.cc
index df1b5b2..facbd05 100644
--- a/examples/static_server.cc
+++ b/examples/file_server.cc
@@ -6,17 +6,17 @@
 #include "webcc/logger.h"
 #include "webcc/server.h"
 
-// -----------------------------------------------------------------------------
-
-void Help(const char* argv0) {
-  std::cout << "Usage: " << argv0 << " <port> <doc_root>" << std::endl;
-  std::cout << "  E.g.," << std::endl;
-  std::cout << "    " << argv0 << " 8080 D:\\www" << std::endl;
+void Help() {
+  std::cout << "Usage:" << std::endl;
+  std::cout << "    file_server <port> <doc_root> [chunk_size]" << std::endl;
+  std::cout << "E.g.," << std::endl;
+  std::cout << "    file_server 8080 D:/www" << std::endl;
+  std::cout << "    file_server 8080 D:/www 10000" << std::endl;
 }
 
 int main(int argc, char* argv[]) {
   if (argc < 3) {
-    Help(argv[0]);
+    Help();
     return 1;
   }
 
@@ -28,6 +28,10 @@ int main(int argc, char* argv[]) {
   try {
     webcc::Server server(port, doc_root);
 
+    if (argc == 4) {
+      server.set_file_chunk_size(std::atoi(argv[3]));
+    }
+
     server.Run();
 
   } catch (const std::exception& e) {
diff --git a/webcc/server.h b/webcc/server.h
index f2d1151..b9ea593 100644
--- a/webcc/server.h
+++ b/webcc/server.h
@@ -27,6 +27,7 @@ public:
   Server& operator=(const Server&) = delete;
 
   void set_file_chunk_size(std::size_t file_chunk_size) {
+    assert(file_chunk_size > 0);
     file_chunk_size_ = file_chunk_size;
   }