diff --git a/.gitignore b/.gitignore
index 2f22da2..4f1387a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,4 +8,4 @@ esm
 dist
 
 timeago.full.min.js
-timeago.min.js
+timeago.min.js
\ No newline at end of file
diff --git a/__tests__/lang/is.spec.ts b/__tests__/lang/is.spec.ts
new file mode 100644
index 0000000..cced76e
--- /dev/null
+++ b/__tests__/lang/is.spec.ts
@@ -0,0 +1,113 @@
+/**
+ * Created by Óli Tómas
+ * Contact: olitomas@olitomas.com
+ */
+import { advanceTo, clear } from 'jest-date-mock';
+import { format, register } from '../../src';
+import is from '../../src/lang/is';
+
+register('is', is);
+
+let date = new Date();
+
+beforeEach(() => {
+  advanceTo(0);
+  date = new Date();
+});
+afterEach(() => {
+  clear();
+});
+describe('is', () => {
+  test('time ago', () => {
+    advanceTo(9 * 1000);
+    expect(format(date, 'is')).toEqual('rétt í þessu');
+
+    advanceTo(30 * 1000);
+    expect(format(date, 'is')).toEqual('30 sekúndum síðan');
+
+    advanceTo(1000 * 60);
+    expect(format(date, 'is')).toEqual('1 mínútu síðan');
+
+    advanceTo(1000 * 60 * 30);
+    expect(format(date, 'is')).toEqual('30 mínútum síðan');
+
+    advanceTo(1000 * 60 * 60);
+    expect(format(date, 'is')).toEqual('1 klukkutíma síðan');
+
+    advanceTo(1000 * 60 * 60 * 8);
+    expect(format(date, 'is')).toEqual('8 klukkutímum síðan');
+
+    advanceTo(1000 * 60 * 60 * 24);
+    expect(format(date, 'is')).toEqual('1 degi síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 3);
+    expect(format(date, 'is')).toEqual('3 dögum síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 7);
+    expect(format(date, 'is')).toEqual('1 viku síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 7 * 3);
+    expect(format(date, 'is')).toEqual('3 vikum síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 31);
+    expect(format(date, 'is')).toEqual('1 mánuði síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 31 * 4);
+    expect(format(date, 'is')).toEqual('4 mánuðum síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 366);
+    expect(format(date, 'is')).toEqual('1 ári síðan');
+
+    advanceTo(1000 * 60 * 60 * 24 * 366 * 10);
+    expect(format(date, 'is')).toEqual('10 árum síðan');
+  });
+  test('time in', () => {
+    advanceTo(-9 * 1000);
+    expect(format(date, 'is')).toEqual('núna');
+
+    advanceTo(-30 * 1000);
+    expect(format(date, 'is')).toEqual('eftir 30 sekúndur');
+
+    advanceTo(-21 * 1000);
+    expect(format(date, 'is')).toEqual('eftir 21 sekúndu');
+
+    advanceTo(-1000 * 60);
+    expect(format(date, 'is')).toEqual('eftir 1 mínútu');
+
+    advanceTo(-1000 * 60 * 30);
+    expect(format(date, 'is')).toEqual('eftir 30 mínútur');
+
+    advanceTo(-1000 * 60 * 31);
+    expect(format(date, 'is')).toEqual('eftir 31 mínútu');
+
+    advanceTo(-1000 * 60 * 60);
+    expect(format(date, 'is')).toEqual('eftir 1 klukkutíma');
+
+    advanceTo(-1000 * 60 * 60 * 8);
+    expect(format(date, 'is')).toEqual('eftir 8 klukkutíma');
+
+    advanceTo(-1000 * 60 * 60 * 24);
+    expect(format(date, 'is')).toEqual('eftir 1 dag');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 3);
+    expect(format(date, 'is')).toEqual('eftir 3 daga');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 7);
+    expect(format(date, 'is')).toEqual('eftir 1 viku');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 7 * 3);
+    expect(format(date, 'is')).toEqual('eftir 3 vikur');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 31);
+    expect(format(date, 'is')).toEqual('eftir 1 mánuð');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 31 * 4);
+    expect(format(date, 'is')).toEqual('eftir 4 mánuði');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 366);
+    expect(format(date, 'is')).toEqual('eftir 1 ár');
+
+    advanceTo(-1000 * 60 * 60 * 24 * 366 * 10);
+    expect(format(date, 'is')).toEqual('eftir 10 ár');
+  });
+});
diff --git a/src/lang/is.ts b/src/lang/is.ts
new file mode 100644
index 0000000..b257178
--- /dev/null
+++ b/src/lang/is.ts
@@ -0,0 +1,22 @@
+const is = ['sekúnd', 'mínút', 'klukkutím', 'd', 'vik', 'mánuð', 'ár'];
+const plural_in = ['ur', 'ur', 'a', 'aga', 'ur', 'i', ''];
+const plural_ago = ['um', 'um', 'um', 'ögum', 'um', 'um', 'um'];
+
+const singular_in = ['u', 'u', 'a', 'ag', 'u', '', ''];
+const singular_ago = ['u', 'u', 'a', 'egi', 'u', 'i', 'i'];
+
+export default function(diff: number, idx: number): [string, string] {
+  if (idx === 0) return ['rétt í þessu', 'núna'];
+  const is_indx = Math.floor(idx / 2);
+  const unit = is[is_indx];
+  let unit_in, unit_ago;
+  if (diff % 10 === 1 && diff !== 11) {
+    unit_in = singular_in[is_indx];
+    unit_ago = singular_ago[is_indx];
+  } else {
+    unit_in = plural_in[is_indx];
+    unit_ago = plural_ago[is_indx];
+  }
+
+  return [`${diff} ${unit + unit_ago} síðan`, `eftir ${diff} ${unit + unit_in}`];
+}