diff --git a/src/deps/picohttpparser.zig b/src/deps/picohttpparser.zig
index db7aefd9b3..0d65f80c35 100644
--- a/src/deps/picohttpparser.zig
+++ b/src/deps/picohttpparser.zig
@@ -12,9 +12,19 @@ pub const struct_phr_chunked_decoder = extern struct {
     bytes_left_in_chunk: usize = 0,
     consume_trailer: u8 = 0,
     _hex_count: u8 = 0,
-    _state: u8 = 0,
+    _state: ChunkedEncodingState = .CHUNKED_IN_CHUNK_SIZE,
 };
 pub extern fn phr_decode_chunked(decoder: *struct_phr_chunked_decoder, buf: [*]u8, bufsz: *usize) isize;
 pub extern fn phr_decode_chunked_is_in_data(decoder: *struct_phr_chunked_decoder) c_int;
 pub const phr_header = struct_phr_header;
 pub const phr_chunked_decoder = struct_phr_chunked_decoder;
+
+pub const ChunkedEncodingState = enum(u8) {
+    CHUNKED_IN_CHUNK_SIZE = 0,
+    CHUNKED_IN_CHUNK_EXT = 1,
+    CHUNKED_IN_CHUNK_DATA = 2,
+    CHUNKED_IN_CHUNK_CRLF = 3,
+    CHUNKED_IN_TRAILERS_LINE_HEAD = 4,
+    CHUNKED_IN_TRAILERS_LINE_MIDDLE = 5,
+    _,
+};
diff --git a/src/http.zig b/src/http.zig
index 9a0df20ddb..8c18fe9e45 100644
--- a/src/http.zig
+++ b/src/http.zig
@@ -1732,17 +1732,16 @@ pub fn onClose(
         return;
     }
     if (in_progress) {
-        // if the peer closed after a full chunk, treat this
-        // as if the transfer had complete, browsers appear to ignore
-        // a missing 0\r\n chunk
         if (client.state.isChunkedEncoding()) {
-            if (picohttp.phr_decode_chunked_is_in_data(&client.state.chunked_decoder) == 0) {
-                const buf = client.state.getBodyBuffer();
-                if (buf.list.items.len > 0) {
+            switch (client.state.chunked_decoder._state) {
+                .CHUNKED_IN_TRAILERS_LINE_HEAD, .CHUNKED_IN_TRAILERS_LINE_MIDDLE => {
+                    // ignore failure if we are in the middle of trailer headers, since we processed all the chunks and trailers are ignored
                     client.state.flags.received_last_chunk = true;
                     client.progressUpdate(comptime is_ssl, if (is_ssl) &http_thread.https_context else &http_thread.http_context, socket);
                     return;
-                }
+                },
+                // here we are in the middle of a chunk so ECONNRESET is expected
+                else => {},
             }
         } else if (client.state.content_length == null and client.state.response_stage == .body) {
             // no content length informed so we are done here
diff --git a/test/js/web/fetch/chunked-trailing.test.js b/test/js/web/fetch/chunked-trailing.test.js
new file mode 100644
index 0000000000..8049a352f9
--- /dev/null
+++ b/test/js/web/fetch/chunked-trailing.test.js
@@ -0,0 +1,606 @@
+import { expect, it } from "bun:test";
+import net from "node:net";
+
+it("handles trailing headers split across packets", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("7\r\n, world\r\n");
+      socket.write("0\r\n");
+      socket.uncork();
+      setTimeout(() => {
+        socket.write("X-Trail: ok\r\n");
+        socket.write('X-Quoted: "quoted value with \\"escapes\\""\r\n\r\n');
+        socket.end();
+      }, 10);
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello, world");
+});
+
+it("handles trailing headers in a single packet", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Trail: ok\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with empty body", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Trail: ok\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("");
+});
+
+it("handles multiple trailing headers", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Trail1: value1\r\n");
+      socket.write("X-Trail2: value2\r\n");
+      socket.write("X-Trail3: value3\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with very long delay", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.uncork();
+      setTimeout(() => {
+        socket.write("X-Trail: ok\r\n\r\n");
+        socket.end();
+      }, 100);
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with byte-by-byte transmission", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.uncork();
+
+      const trailer = "X-Trail: ok\r\n\r\n";
+      let i = 0;
+
+      function writeNextByte() {
+        if (i < trailer.length) {
+          socket.write(trailer[i]);
+          i++;
+          setTimeout(writeNextByte, 5);
+        } else {
+          socket.end();
+        }
+      }
+
+      setTimeout(writeNextByte, 10);
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with malformed format (missing final CRLF)", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Trail: ok\r\n"); // Missing final CRLF
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with extremely large values", async () => {
+  const largeValue = "x".repeat(16384); // 16KB value
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write(`X-Large-Trail: ${largeValue}\r\n\r\n`);
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles connection close during trailing headers", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Trail: partial\r\n");
+      socket.end(); // Close connection abruptly
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with multiple header lines", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Trail-1: value1\r\n");
+      socket.write("X-Trail-2: value2\r\n");
+      socket.write("X-Trail-3: value3\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers with empty values", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+      socket.write("X-Empty-Trail: \r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles delayed trailing headers", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+      socket.write("5\r\nHello\r\n");
+      socket.write("0\r\n");
+
+      // Simulate delay before sending trailing headers
+      setTimeout(() => {
+        socket.write("X-Delayed-Trail: value\r\n\r\n");
+        socket.end();
+      }, 100);
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles trailing headers after the final chunk only", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // First chunk
+      socket.write("5\r\nHello\r\n");
+
+      // Second chunk
+      socket.write("5\r\nWorld\r\n");
+
+      // Final chunk with trailing headers
+      socket.write("0\r\n");
+      socket.write("X-Final-Trail: final\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("HelloWorld");
+});
+
+it("handles chunked extensions with empty extension", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Chunk with empty extension
+      socket.write("5;\r\nHello\r\n");
+      socket.write("0\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles chunked extensions with simple key", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Chunk with simple extension
+      socket.write("5;foo\r\nHello\r\n");
+      socket.write("0\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles chunked extensions with key-value pair", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Chunk with key-value extension
+      socket.write("5;foo=bar\r\nHello\r\n");
+      socket.write("0\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles chunked extensions with quoted value", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Chunk with quoted value extension
+      socket.write('5;foo="bar baz"\r\nHello\r\n');
+      socket.write("0\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("handles chunked extensions on multiple chunks", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // First chunk with extension
+      socket.write("5;ext=1\r\nHello\r\n");
+
+      // Second chunk with different extension
+      socket.write("5;ext=2\r\nWorld\r\n");
+
+      // Final chunk with extension
+      socket.write("0;ext=final\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("HelloWorld");
+});
+
+it("handles chunked extensions with trailing headers", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Chunks with extensions
+      socket.write("5;ext=first\r\nHello\r\n");
+      socket.write("5;ext=second\r\nWorld\r\n");
+
+      // Final chunk with extension and trailing headers
+      socket.write("0;ext=final\r\n");
+      socket.write("X-Trailer: value\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("HelloWorld");
+});
+
+it("handles chunked extensions with special characters", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Extension with special characters in quoted value
+      socket.write('5;ext="!@#$%^&*()"\r\nHello\r\n');
+      socket.write("0\r\n\r\n");
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  const address = await promise;
+  const res = await fetch(`http://localhost:${address.port}`);
+  expect(res.status).toBe(200);
+  expect(await res.text()).toBe("Hello");
+});
+
+it("proper error if missing zero-length chunk", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Valid chunk
+      socket.write("5\r\nHello\r\n");
+
+      // End the connection abruptly
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  try {
+    const address = await promise;
+    const response = await fetch(`http://localhost:${address.port}`);
+    expect(response.status).toBe(200);
+    await response.text();
+    expect.unreachable();
+  } catch (e) {
+    expect(e?.code).toBe("ECONNRESET");
+  }
+});
+it("proper error if missing data in middle of chunk extension", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Valid chunk
+      socket.write("5\r\nHello\r\n");
+
+      // Malformed chunk - missing CRLF after extension
+      socket.write("5;ext=foo");
+
+      // End the connection abruptly
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  try {
+    const address = await promise;
+    await fetch(`http://localhost:${address.port}`).then(res => res.text());
+    expect.unreachable();
+  } catch (e) {
+    expect(e?.code).toBe("ECONNRESET");
+  }
+});
+
+it("proper error if missing CRLF after chunk data", async () => {
+  const { promise, resolve } = Promise.withResolvers();
+  await using server = net
+    .createServer(socket => {
+      socket.write("HTTP/1.1 200 OK\r\n");
+      socket.write("Content-Type: text/plain\r\n");
+      socket.write("Transfer-Encoding: chunked\r\n");
+      socket.write("\r\n");
+
+      // Valid chunk
+      socket.write("5\r\nHello\r\n");
+
+      // Malformed chunk - missing CRLF after chunk data
+      socket.write("5\r\nWorldX");
+
+      // End the connection abruptly
+      socket.end();
+    })
+    .listen(0, "localhost", () => {
+      resolve(server.address());
+    });
+
+  try {
+    const address = await promise;
+    await fetch(`http://localhost:${address.port}`).then(res => res.text());
+    expect.unreachable();
+  } catch (e) {
+    expect(e?.code).toBe("InvalidHTTPResponse");
+  }
+});