diff --git a/src/util/util.js b/src/util/util.js
index a4b4a71..bd6103a 100644
--- a/src/util/util.js
+++ b/src/util/util.js
@@ -19,8 +19,36 @@ exports.find = (buf, byte) => {
   return -1
 }
 
+// Adapted from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString#Polyfill
+const timestampWithOffsetToISOString = (timestamp, offset) => {
+  const offsetHours = Math.floor(offset / 100)
+  const offsetMinutes = offset % 100
+
+  const pad = (number) => number < 10 ? '0' + number : number
+
+  const date = new Date((timestamp + offsetHours * 3600 + offsetMinutes * 60) * 1000)
+  const dateString = date.getUTCFullYear() +
+    '-' + pad(date.getUTCMonth() + 1) +
+    '-' + pad(date.getUTCDate()) +
+    'T' + pad(date.getUTCHours()) +
+    ':' + pad(date.getUTCMinutes()) +
+    ':' + pad(date.getUTCSeconds()) +
+    (offset >= 0 ? '+' : '-') + pad(offsetHours) +
+    ':' + pad(offsetMinutes)
+  return dateString
+}
+
+// Last 6 characters will always be of the form ±hh:mm
+const isoStringToTimestampWithOffset = (isoString) => {
+  const offset = isoString.slice(-6, -3) + isoString.slice(-2)
+  const offsetAsNumber = parseInt(offset)
+  const offsetInSeconds = Math.floor(offsetAsNumber / 100) * 3600 + (offsetAsNumber % 100) * 60
+
+  return Math.floor(new Date(isoString.slice(0, -6) + 'Z') / 1000) - offsetInSeconds + ' ' + offset
+}
+
 exports.parsePersonLine = (line) => {
-  let matched = line.match(/^(([^<]+)\s)?\s?<([^>]+)>\s?(\d+\s[+\-\d]+)?$/)
+  let matched = line.match(/^(([^<]+)\s)?\s?<([^>]+)>\s?(?:(\d+)\s([+-]\d+))?$/)
   if (matched === null) {
     return null
   }
@@ -28,7 +56,7 @@ exports.parsePersonLine = (line) => {
   return {
     name: matched[2],
     email: matched[3],
-    date: matched[4]
+    date: matched[4] && matched[5] && timestampWithOffsetToISOString(parseInt(matched[4]), parseInt(matched[5]))
   }
 }
 
@@ -39,7 +67,7 @@ exports.serializePersonLine = (node) => {
   }
   parts.push('<' + node.email + '>')
   if (node.date) {
-    parts.push(node.date)
+    parts.push(isoStringToTimestampWithOffset(node.date))
   }
 
   return parts.join(' ')
diff --git a/test/parse.spec.js b/test/parse.spec.js
index aa7c6d0..163fe10 100644
--- a/test/parse.spec.js
+++ b/test/parse.spec.js
@@ -22,7 +22,7 @@ describe('utils', () => {
       expect(info).to.exist()
       expect(info.name).to.equal('Someone')
       expect(info.email).to.equal('some@one.somewhere')
-      expect(info.date).to.equal('123456 +0123')
+      expect(info.date).to.equal('1970-01-02T11:40:36+01:23')
       done()
     })
 
@@ -31,7 +31,7 @@ describe('utils', () => {
       expect(info).to.exist()
       expect(info.name).to.equal('So Me One')
       expect(info.email).to.equal('some@one.somewhere')
-      expect(info.date).to.equal('123456 +0123')
+      expect(info.date).to.equal('1970-01-02T11:40:36+01:23')
       done()
     })
 
@@ -40,7 +40,7 @@ describe('utils', () => {
       expect(info).to.exist()
       expect(info.name).to.not.exist()
       expect(info.email).to.equal('some@one.somewhere')
-      expect(info.date).to.equal('123456 +0123')
+      expect(info.date).to.equal('1970-01-02T11:40:36+01:23')
       done()
     })
 
@@ -49,7 +49,7 @@ describe('utils', () => {
       expect(info).to.exist()
       expect(info.name).to.not.exist()
       expect(info.email).to.equal('some@one.somewhere')
-      expect(info.date).to.equal('123456 +0123')
+      expect(info.date).to.equal('1970-01-02T11:40:36+01:23')
       done()
     })
 
@@ -58,7 +58,7 @@ describe('utils', () => {
       expect(info).to.exist()
       expect(info.name).to.equal('Some One & Other One')
       expect(info.email).to.equal('some@one.somewhere, other@one.elsewhere')
-      expect(info.date).to.equal('987654 +4321')
+      expect(info.date).to.equal('1970-01-14T05:41:54+43:21')
       done()
     })
 
diff --git a/test/resolver.spec.js b/test/resolver.spec.js
index 66e409d..a076448 100644
--- a/test/resolver.spec.js
+++ b/test/resolver.spec.js
@@ -30,12 +30,12 @@ describe('IPLD format resolver (local)', () => {
       author: {
         name: 'John Doe',
         email: 'johndoe@example.com',
-        date: '1497302532 +0200'
+        date: '2017-06-12T23:22:12+02:00'
       },
       committer: {
         name: 'John Doe',
         email: 'johndoe@example.com',
-        date: '1497302532 +0200'
+        date: '2017-06-12T23:22:12+02:00'
       },
       encoding: 'ISO-8859-1',
       message: 'Encoded\n'
@@ -49,7 +49,7 @@ describe('IPLD format resolver (local)', () => {
       tagger: {
         name: 'John Doe',
         email: 'johndoe@example.com',
-        date: '1497302532 +0200'
+        date: '2017-06-12T23:22:12+02:00'
       },
       message: 'A message\n'
     }
diff --git a/test/util.spec.js b/test/util.spec.js
index a222167..759cdcb 100644
--- a/test/util.spec.js
+++ b/test/util.spec.js
@@ -18,7 +18,7 @@ describe('IPLD format util', () => {
     tagger: {
       name: 'John Doe',
       email: 'johndoe@example.com',
-      date: '1497302532 +0200'
+      date: '2017-06-12T23:22:12+02:00'
     },
     message: 'A message\n'
   }
@@ -29,7 +29,7 @@ describe('IPLD format util', () => {
       expect(Buffer.isBuffer(serialized)).to.equal(true)
       ipldGit.util.deserialize(serialized, (err, deserialized) => {
         expect(err).to.not.exist()
-        expect(tagNode).to.eql(deserialized)
+        expect(deserialized).to.eql(tagNode)
         done()
       })
     })