diff --git a/integration-tests/nghttpx_http2_test.go b/integration-tests/nghttpx_http2_test.go
index 11f2b0f3..ef261ed3 100644
--- a/integration-tests/nghttpx_http2_test.go
+++ b/integration-tests/nghttpx_http2_test.go
@@ -1548,6 +1548,26 @@ func TestH2H1HTTPSRedirectPort(t *testing.T) {
 	}
 }
 
+// TestH2H1Code204 tests that 204 response without content-length, and
+// transfer-encoding is valid.
+func TestH2H1Code204(t *testing.T) {
+	st := newServerTester(nil, t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNoContent)
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestH2H1Code204",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http2() = %v", err)
+	}
+
+	if got, want := res.status, 204; got != want {
+		t.Errorf("status = %v; want %v", got, want)
+	}
+}
+
 // TestH2H1GracefulShutdown tests graceful shutdown.
 func TestH2H1GracefulShutdown(t *testing.T) {
 	st := newServerTester(nil, t, noopHandler)
@@ -2159,6 +2179,26 @@ func TestH2H2DNS(t *testing.T) {
 	}
 }
 
+// TestH2H2Code204 tests that 204 response without content-length, and
+// transfer-encoding is valid.
+func TestH2H2Code204(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNoContent)
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestH2H2Code204",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http2() = %v", err)
+	}
+
+	if got, want := res.status, 204; got != want {
+		t.Errorf("status = %v; want %v", got, want)
+	}
+}
+
 // TestH2APIBackendconfig exercise backendconfig API endpoint routine
 // for successful case.
 func TestH2APIBackendconfig(t *testing.T) {
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index aec721be..8c82b3df 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -892,13 +892,12 @@ int htp_hdrs_completecb(http_parser *htp) {
     if (resp.fs.parse_content_length() != 0) {
       return -1;
     }
-    if (resp.fs.content_length != 0) {
-      return -1;
-    }
     if (resp.fs.content_length == 0) {
       auto cl = resp.fs.header(http2::HD_CONTENT_LENGTH);
       assert(cl);
       http2::erase_header(cl);
+    } else if (resp.fs.content_length != -1) {
+      return -1;
     }
   } else if (resp.http_status / 100 == 1 ||
              (resp.http_status == 200 && req.method == HTTP_CONNECT)) {