diff --git a/index.js b/index.js
index 6aedf52..cb8f8a8 100644
--- a/index.js
+++ b/index.js
@@ -9,6 +9,8 @@
 const config = require('./config')
 const bot = require('./bot')
 const crypto = require('crypto')
+const lru = require('lru-cache')
+const previouslyFundedContracts = lru(10)
 
 const express = require('express')
 const cors = require('cors')
@@ -35,8 +37,9 @@ app.post(`${config.urlEndpoint}`, jsonParser, function (req, res, next) {
   if (validation.correct) {
     setTimeout(async () => {
       try {
-        await processRequest(req)
-        bot.info(`issue well funded: ${req.body.issue.url}`)
+        if (await processRequest(req)) {
+          bot.info(`Issue well funded: ${req.body.issue.url}`)
+        }
       } catch (err) {
         bot.error(`Error processing request: ${req.body.issue.url}`)
         bot.error(err)
@@ -82,11 +85,22 @@ function validateRequest (req) {
 
 async function processRequest (req) {
   const to = bot.getAddress(req)
+
+  const previousHash = previouslyFundedContracts.get(to)
+  if (previousHash) {
+    bot.info(`Issue has been funded before (tx hash=${previousHash}), ignoring`)
+    return null
+  }
+
   const amount = await bot.getAmount(req)
   const gasPrice = await bot.getGasPrice()
-  const hash = await bot.sendTransaction(to, amount, gasPrice)
+  const transaction = await bot.sendTransaction(to, amount, gasPrice)
 
-  bot.logTransaction(hash)
+  previouslyFundedContracts.set(to, transaction.hash)
+
+  bot.logTransaction(transaction)
+
+  return transaction
 }
 
 const port = process.env.PORT || 8181
diff --git a/package-lock.json b/package-lock.json
index 6005bc6..c0b0677 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1682,7 +1682,6 @@
       "version": "4.1.2",
       "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-4.1.2.tgz",
       "integrity": "sha512-wgeVXhrDwAWnIF/yZARsFnMBtdFXOg1b8RIrhilp+0iDYN4mdQcNZElDZ0e4B64BhaxeQ5zN7PMyvu7we1kPeQ==",
-      "dev": true,
       "requires": {
         "pseudomap": "1.0.2",
         "yallist": "2.1.2"
@@ -2072,8 +2071,7 @@
     "pseudomap": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/pseudomap/-/pseudomap-1.0.2.tgz",
-      "integrity": "sha1-8FKijacOYYkX7wqKw0wa5aaChrM=",
-      "dev": true
+      "integrity": "sha1-8FKijacOYYkX7wqKw0wa5aaChrM="
     },
     "qs": {
       "version": "6.5.1",
@@ -2608,8 +2606,7 @@
     "yallist": {
       "version": "2.1.2",
       "resolved": "https://registry.npmjs.org/yallist/-/yallist-2.1.2.tgz",
-      "integrity": "sha1-HBH5IY8HYImkfdUS+TxmmaaoHVI=",
-      "dev": true
+      "integrity": "sha1-HBH5IY8HYImkfdUS+TxmmaaoHVI="
     }
   }
 }
diff --git a/package.json b/package.json
index 712a21e..752de00 100644
--- a/package.json
+++ b/package.json
@@ -22,6 +22,7 @@
     "express": "^4.15.2",
     "helmet": "^3.9.0",
     "lodash": "^4.17.4",
+    "lru-cache": "^4.1.2",
     "winston": "^3.0.0-rc3"
   },
   "devDependencies": {