diff --git a/http3/headers.go b/http3/headers.go
index ec3fc0dd..79c070b5 100644
--- a/http3/headers.go
+++ b/http3/headers.go
@@ -60,6 +60,8 @@ func parseHeaders(headers []qpack.HeaderField, isRequest bool) (header, error) {
 			case ":status":
 				hdr.Status = h.Value
 				isResponsePseudoHeader = true
+			default:
+				return header{}, fmt.Errorf("unknown pseudo header: %s", h.Name)
 			}
 			if isRequest && isResponsePseudoHeader {
 				return header{}, fmt.Errorf("invalid request pseudo header: %s", h.Name)
diff --git a/http3/headers_test.go b/http3/headers_test.go
index 72233680..70fac997 100644
--- a/http3/headers_test.go
+++ b/http3/headers_test.go
@@ -44,6 +44,17 @@ var _ = Describe("Request", func() {
 		Expect(err).To(MatchError("header field is not lower-case: Content-Length"))
 	})
 
+	It("rejects unknown pseudo headers", func() {
+		headers := []qpack.HeaderField{
+			{Name: ":path", Value: "/foo"},
+			{Name: ":authority", Value: "quic.clemente.io"},
+			{Name: ":method", Value: "GET"},
+			{Name: ":foo", Value: "bar"},
+		}
+		_, err := requestFromHeaders(headers)
+		Expect(err).To(MatchError("unknown pseudo header: :foo"))
+	})
+
 	It("rejects invalid field names", func() {
 		headers := []qpack.HeaderField{
 			{Name: ":path", Value: "/foo"},