diff --git a/CHANGELOG.md b/CHANGELOG.md
index aea0df1fa..caa87b697 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Now when switching networks the extension does not restart
 - Cleanup decimal bugs in our gas inputs.
 - Fix bug where submit button was enabled for invalid gas inputs.
+- Now enforce 95% of block's gasLimit to protect users.
 
 ## 3.7.0 2017-5-23
 
diff --git a/app/scripts/lib/tx-utils.js b/app/scripts/lib/tx-utils.js
index 76b311653..8cf304d0b 100644
--- a/app/scripts/lib/tx-utils.js
+++ b/app/scripts/lib/tx-utils.js
@@ -21,19 +21,30 @@ module.exports = class txProviderUtils {
     this.query.getBlockByNumber('latest', true, (err, block) => {
       if (err) return cb(err)
       async.waterfall([
+        self.setBlockGasLimit.bind(self, txMeta, block.gasLimit),
         self.estimateTxGas.bind(self, txMeta, block.gasLimit),
         self.setTxGas.bind(self, txMeta, block.gasLimit),
       ], cb)
     })
   }
 
+  setBlockGasLimit (txMeta, blockGasLimitHex, cb) {
+    const blockGasLimitBN = hexToBn(blockGasLimitHex)
+    const saferGasLimitBN = blockGasLimitBN.muln(0.95)
+    txMeta.blockGasLimit = bnToHex(saferGasLimitBN)
+    cb()
+    return
+  }
+
   estimateTxGas (txMeta, blockGasLimitHex, cb) {
     const txParams = txMeta.txParams
     // check if gasLimit is already specified
     txMeta.gasLimitSpecified = Boolean(txParams.gas)
     // if not, fallback to block gasLimit
     if (!txMeta.gasLimitSpecified) {
-      txParams.gas = blockGasLimitHex
+      const blockGasLimitBN = hexToBn(blockGasLimitHex)
+      const saferGasLimitBN = blockGasLimitBN.muln(0.95)
+      txParams.gas = bnToHex(saferGasLimitBN)
     }
     // run tx, see if it will OOG
     this.query.estimateGas(txParams, cb)
diff --git a/ui/app/components/pending-tx.js b/ui/app/components/pending-tx.js
index d66d98dd5..b46f715bc 100644
--- a/ui/app/components/pending-tx.js
+++ b/ui/app/components/pending-tx.js
@@ -47,6 +47,7 @@ PendingTx.prototype.render = function () {
   // Gas
   const gas = txParams.gas
   const gasBn = hexToBn(gas)
+  const safeGasLimit = parseInt(txMeta.blockGasLimit)
 
   // Gas Price
   const gasPrice = txParams.gasPrice || MIN_GAS_PRICE_BN.toString(16)
@@ -159,6 +160,7 @@ PendingTx.prototype.render = function () {
                   scale: 0,
                   // The hard lower limit for gas.
                   min: MIN_GAS_LIMIT_BN.toString(10),
+                  max: safeGasLimit,
                   suffix: 'UNITS',
                   style: {
                     position: 'relative',