diff --git a/http3/transport.go b/http3/transport.go
index 245d7157..4a863913 100644
--- a/http3/transport.go
+++ b/http3/transport.go
@@ -161,27 +161,37 @@ func (t *Transport) init() error {
 
 // RoundTripOpt is like RoundTrip, but takes options.
 func (t *Transport) RoundTripOpt(req *http.Request, opt RoundTripOpt) (*http.Response, error) {
+	rsp, err := t.roundTripOpt(req, opt)
+	if err != nil {
+		if req.Body != nil {
+			req.Body.Close()
+		}
+		return nil, err
+	}
+	return rsp, nil
+}
+
+func (t *Transport) roundTripOpt(req *http.Request, opt RoundTripOpt) (*http.Response, error) {
 	t.initOnce.Do(func() { t.initErr = t.init() })
 	if t.initErr != nil {
 		return nil, t.initErr
 	}
 
 	if req.URL == nil {
-		closeRequestBody(req)
 		return nil, errors.New("http3: nil Request.URL")
 	}
 	if req.URL.Scheme != "https" {
-		closeRequestBody(req)
 		return nil, fmt.Errorf("http3: unsupported protocol scheme: %s", req.URL.Scheme)
 	}
 	if req.URL.Host == "" {
-		closeRequestBody(req)
 		return nil, errors.New("http3: no Host in request URL")
 	}
 	if req.Header == nil {
-		closeRequestBody(req)
 		return nil, errors.New("http3: nil Request.Header")
 	}
+	if req.Method != "" && !validMethod(req.Method) {
+		return nil, fmt.Errorf("http3: invalid method %q", req.Method)
+	}
 	for k, vv := range req.Header {
 		if !httpguts.ValidHeaderFieldName(k) {
 			return nil, fmt.Errorf("http3: invalid http header field name %q", k)
@@ -193,11 +203,6 @@ func (t *Transport) RoundTripOpt(req *http.Request, opt RoundTripOpt) (*http.Res
 		}
 	}
 
-	if req.Method != "" && !validMethod(req.Method) {
-		closeRequestBody(req)
-		return nil, fmt.Errorf("http3: invalid method %q", req.Method)
-	}
-
 	trace := httptrace.ContextClientTrace(req.Context())
 	hostname := authorityAddr(hostnameFromURL(req.URL))
 	traceGetConn(trace, hostname)
@@ -415,12 +420,6 @@ func (t *Transport) Close() error {
 	return nil
 }
 
-func closeRequestBody(req *http.Request) {
-	if req.Body != nil {
-		req.Body.Close()
-	}
-}
-
 func validMethod(method string) bool {
 	/*
 				     Method         = "OPTIONS"                ; Section 9.2
diff --git a/http3/transport_test.go b/http3/transport_test.go
index 9c4e06b0..bf136617 100644
--- a/http3/transport_test.go
+++ b/http3/transport_test.go
@@ -512,14 +512,18 @@ var _ = Describe("Transport", func() {
 
 		It("rejects requests with invalid header name fields", func() {
 			req.Header.Add("foobär", "value")
+			req.Body = &mockBody{}
 			_, err := tr.RoundTrip(req)
 			Expect(err).To(MatchError("http3: invalid http header field name \"foobär\""))
+			Expect(req.Body.(*mockBody).closed).To(BeTrue())
 		})
 
 		It("rejects requests with invalid header name values", func() {
 			req.Header.Add("foo", string([]byte{0x7}))
+			req.Body = &mockBody{}
 			_, err := tr.RoundTrip(req)
 			Expect(err.Error()).To(ContainSubstring("http3: invalid http header field value"))
+			Expect(req.Body.(*mockBody).closed).To(BeTrue())
 		})
 
 		It("rejects requests with an invalid request method", func() {