diff --git a/README.md b/README.md
index d4c0b677..adc9ce73 100644
--- a/README.md
+++ b/README.md
@@ -429,7 +429,7 @@ void start_server() {
         auto boundary = req.get_boundary();
         multipart_reader_t multipart(req.get_conn());
         while (true) {
-          auto part_head = co_await multipart.read_part_head();
+          auto part_head = co_await multipart.read_part_head(boundary);
           if (part_head.ec) {
             co_return;
           }
diff --git a/example/main.cpp b/example/main.cpp
index 6af3de68..33d36fb8 100644
--- a/example/main.cpp
+++ b/example/main.cpp
@@ -301,16 +301,14 @@ async_simple::coro::Lazy<void> basic_usage() {
       "/form_data",
       [](coro_http_request &req,
          coro_http_response &resp) -> async_simple::coro::Lazy<void> {
-        if (req.get_content_type() != content_type::multipart) {
-          resp.set_status_and_content(status_type::bad_request,
-                                      "bad request, not multipart request");
-          co_return;
-        }
+        assert(req.get_content_type() == content_type::multipart);
         auto boundary = req.get_boundary();
         multipart_reader_t multipart(req.get_conn());
         while (true) {
-          auto part_head = co_await multipart.read_part_head();
+          auto part_head = co_await multipart.read_part_head(boundary);
           if (part_head.ec) {
+            resp.set_status_and_content(status_type::bad_request,
+                                        "bad_request");
             co_return;
           }
 
diff --git a/include/cinatra/coro_http_client.hpp b/include/cinatra/coro_http_client.hpp
index 2c3501e3..3b92efa4 100644
--- a/include/cinatra/coro_http_client.hpp
+++ b/include/cinatra/coro_http_client.hpp
@@ -1640,7 +1640,7 @@ class coro_http_client : public std::enable_shared_from_this<coro_http_client> {
     std::string boundary = std::string{parser_.get_boundary()};
     multipart_reader_t multipart(this);
     while (true) {
-      auto part_head = co_await multipart.read_part_head();
+      auto part_head = co_await multipart.read_part_head(boundary);
       if (part_head.ec) {
         co_return part_head.ec;
       }
diff --git a/include/cinatra/coro_http_request.hpp b/include/cinatra/coro_http_request.hpp
index ea6574fd..a41df18e 100644
--- a/include/cinatra/coro_http_request.hpp
+++ b/include/cinatra/coro_http_request.hpp
@@ -184,7 +184,13 @@ class coro_http_request {
     if (content_type.empty()) {
       return {};
     }
-    return content_type.substr(content_type.rfind("=") + 1);
+
+    auto pos = content_type.rfind("=");
+    if (pos == std::string_view::npos) {
+      return "";
+    }
+
+    return content_type.substr(pos + 1);
   }
 
   coro_http_connection *get_conn() { return conn_; }
@@ -278,7 +284,7 @@ class coro_http_request {
   http_parser &parser_;
   std::string_view body_;
   coro_http_connection *conn_;
-  bool is_websocket_;
+  bool is_websocket_ = false;
   std::vector<std::string> aspect_data_;
   std::string cached_session_id_;
 };
diff --git a/include/cinatra/multipart.hpp b/include/cinatra/multipart.hpp
index d40aaa71..b85b5001 100644
--- a/include/cinatra/multipart.hpp
+++ b/include/cinatra/multipart.hpp
@@ -11,7 +11,12 @@ class multipart_reader_t {
         head_buf_(conn_->head_buf_),
         chunked_buf_(conn_->chunked_buf_) {}
 
-  async_simple::coro::Lazy<part_head_t> read_part_head() {
+  async_simple::coro::Lazy<part_head_t> read_part_head(
+      std::string_view boundary) {
+    if (boundary.empty()) {
+      co_return part_head_t{std::make_error_code(std::errc::protocol_error)};
+    }
+
     if (head_buf_.size() > 0) {
       const char *data_ptr = asio::buffer_cast<const char *>(head_buf_.data());
       chunked_buf_.sputn(data_ptr, head_buf_.size());
diff --git a/lang/coroutine_based_http_lib.md b/lang/coroutine_based_http_lib.md
index cfda7801..8487d0a1 100644
--- a/lang/coroutine_based_http_lib.md
+++ b/lang/coroutine_based_http_lib.md
@@ -528,7 +528,7 @@ async_simple::coro::Lazy<void> byte_ranges_download() {
         auto boundary = req.get_boundary();
         multipart_reader_t multipart(req.get_conn());
         while (true) {
-          auto part_head = co_await multipart.read_part_head();
+          auto part_head = co_await multipart.read_part_head(boundary);
           if (part_head.ec) {
             co_return;
           }
diff --git a/lang/english/README.md b/lang/english/README.md
index 82cf4579..c7e9ae49 100644
--- a/lang/english/README.md
+++ b/lang/english/README.md
@@ -387,7 +387,7 @@ void start_server() {
         auto boundary = req.get_boundary();
         multipart_reader_t multipart(req.get_conn());
         while (true) {
-          auto part_head = co_await multipart.read_part_head();
+          auto part_head = co_await multipart.read_part_head(boundary);
           if (part_head.ec) {
             co_return;
           }
diff --git a/tests/test_cinatra.cpp b/tests/test_cinatra.cpp
index a66b8fa3..d1a3139c 100644
--- a/tests/test_cinatra.cpp
+++ b/tests/test_cinatra.cpp
@@ -687,7 +687,7 @@ TEST_CASE("test upload file") {
         auto boundary = req.get_boundary();
         multipart_reader_t multipart(req.get_conn());
         while (true) {
-          auto part_head = co_await multipart.read_part_head();
+          auto part_head = co_await multipart.read_part_head(boundary);
           if (part_head.ec) {
             co_return;
           }
@@ -897,7 +897,7 @@ TEST_CASE("test coro_http_client multipart upload") {
         auto boundary = req.get_boundary();
         multipart_reader_t multipart(req.get_conn());
         while (true) {
-          auto part_head = co_await multipart.read_part_head();
+          auto part_head = co_await multipart.read_part_head(boundary);
           if (part_head.ec) {
             co_return;
           }