diff --git a/CHANGELOG.md b/CHANGELOG.md
index 73fde7504..e75502159 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Current Master
 
+- Fix gas estimation bug.
 - Fix github link on info page to point at current repository.
 
 ## 2.13.6 2016-10-26
diff --git a/app/scripts/lib/idStore.js b/app/scripts/lib/idStore.js
index 46d53c4e1..1010a5789 100644
--- a/app/scripts/lib/idStore.js
+++ b/app/scripts/lib/idStore.js
@@ -287,11 +287,11 @@ IdentityStore.prototype.checkForDelegateCall = function (codeHex) {
   }
 }
 
-IdentityStore.prototype.addGasBuffer = function (gasHex) {
-  var gas = new BN(gasHex, 16)
-  var buffer = new BN('100000', 10)
-  var result = gas.add(buffer)
-  return ethUtil.addHexPrefix(result.toString(16))
+const gasBuffer = new BN('100000', 10)
+IdentityStore.prototype.addGasBuffer = function (gas) {
+  const bnGas = new BN(ethUtil.stripHexPrefix(gas), 16)
+  const correct = bnGas.add(gasBuffer)
+  return ethUtil.addHexPrefix(correct.toString(16))
 }
 
 // comes from metamask ui
diff --git a/test/unit/idStore-test.js b/test/unit/idStore-test.js
index da465f511..46b3d4809 100644
--- a/test/unit/idStore-test.js
+++ b/test/unit/idStore-test.js
@@ -142,20 +142,47 @@ describe('IdentityStore', function() {
   })
 
   describe('#addGasBuffer', function() {
-    const idStore = new IdentityStore({
-      configManager: configManagerGen(),
-      ethStore: {
-        addAccount(acct) { accounts.push(ethUtil.addHexPrefix(acct)) },
-      },
+    it('formats the result correctly', function() {
+      const idStore = new IdentityStore({
+        configManager: configManagerGen(),
+        ethStore: {
+          addAccount(acct) { accounts.push(ethUtil.addHexPrefix(acct)) },
+        },
+      })
+
+      const gas = '0x01'
+      const bnGas = new BN(gas, 16)
+      const result = idStore.addGasBuffer(gas)
+      const bnResult = new BN(result, 16)
+
+      assert.ok(bnResult.gt(gas), 'added more gas as buffer.')
+      assert.equal(result.indexOf('0x'), 0, 'include hex prefix')
     })
 
-    const gas = '0x01'
-    const bnGas = new BN(gas, 16)
-    const result = idStore.addGasBuffer(gas)
-    const bnResult = new BN(result, 16)
+    it('buffers reasonably', function() {
+      const idStore = new IdentityStore({
+        configManager: configManagerGen(),
+        ethStore: {
+          addAccount(acct) { accounts.push(ethUtil.addHexPrefix(acct)) },
+        },
+      })
 
-    assert.ok(bnResult.gt(gas), 'added more gas as buffer.')
-    assert.equal(result.indexOf('0x'), 0, 'include hex prefix')
+      const gas = '0x04ee59' // Actual estimated gas example
+      const tooBigOutput = '0x80674f9' // Actual bad output
+      const bnGas = new BN(ethUtil.stripHexPrefix(gas), 16)
+      const correctBuffer = new BN('100000', 10)
+      const correct = bnGas.add(correctBuffer)
+
+      const tooBig = new BN(tooBigOutput, 16)
+      const result = idStore.addGasBuffer(gas)
+      const bnResult = new BN(ethUtil.stripHexPrefix(result), 16)
+
+      assert.equal(result.indexOf('0x'), 0, 'included hex prefix')
+      assert(bnResult.gt(bnGas), 'Estimate increased in value.')
+      assert.equal(bnResult.sub(bnGas).toString(10), '100000', 'added 100k gas')
+      assert.equal(result, '0x' + correct.toString(16), 'Added the right amount')
+      assert.notEqual(result, tooBigOutput, 'not that bad estimate')
+    })
   })
 
   describe('#checkForDelegateCall', function() {
@@ -169,4 +196,5 @@ describe('IdentityStore', function() {
     var result = idStore.checkForDelegateCall(delegateCallCode)
     assert.equal(result, true, 'no delegate call in provided code')
   })
+
 })