diff --git a/lib/routes.js b/lib/routes.js
index 074de437..d71fe074 100644
--- a/lib/routes.js
+++ b/lib/routes.js
@@ -25,6 +25,7 @@ const argv = require('minimist')(process.argv.slice(2))
 
 const CLOCK_SKEW = 60 * 1000
 const REQUEST_TTL = 3 * 60 * 1000
+const SERIALIZATION_FAILURE_CODE = '40001'
 
 const pids = {}
 const reboots = {}
@@ -134,6 +135,7 @@ function postTx (req, res, next) {
       return res.json(tx)
     })
     .catch(err => {
+      if (err.code === SERIALIZATION_FAILURE_CODE) return res.status(204).json({})
       if (err instanceof E.StaleTxError) return res.status(409).json({})
       if (err instanceof E.RatchetError) return res.status(409).json({})