diff --git a/src/http.zig b/src/http.zig
index d4f2c05d63..00cbf2f032 100644
--- a/src/http.zig
+++ b/src/http.zig
@@ -663,7 +663,7 @@ pub fn buildRequest(this: *HTTPClient, body_len: usize) picohttp.Request {
 
     if (body_len > 0 or this.method.hasRequestBody()) {
         if (this.flags.is_streaming_request_body) {
-            if (add_transfer_encoding) {
+            if (add_transfer_encoding and this.flags.upgrade_state == .none) {
                 request_headers_buf[header_count] = chunked_encoded_header;
                 header_count += 1;
             }
diff --git a/src/http/HTTPThread.zig b/src/http/HTTPThread.zig
index 8ed4f2f52a..d6946798e8 100644
--- a/src/http/HTTPThread.zig
+++ b/src/http/HTTPThread.zig
@@ -323,8 +323,8 @@ fn drainEvents(this: *@This()) void {
                             if (client.state.original_request_body == .stream) {
                                 var stream = &client.state.original_request_body.stream;
                                 stream.ended = ended;
-                                if (messageType == .endChunked) {
-                                    // only send the 0-length chunk if the request body is chunked
+                                if (messageType == .endChunked and client.flags.upgrade_state != .upgraded) {
+                                    // only send the 0-length chunk if the request body is chunked and not upgraded
                                     client.writeToStream(is_tls, socket, bun.http.end_of_chunked_http1_1_encoding_response_body);
                                 } else {
                                     client.flushStream(is_tls, socket);