diff --git a/urbantz/tests/test_coordinates.py b/urbantz/tests/test_coordinates.py
index 50f2712..4766f9c 100644
--- a/urbantz/tests/test_coordinates.py
+++ b/urbantz/tests/test_coordinates.py
@@ -1,5 +1,5 @@
 from unittest import TestCase
-from math import trunc, floor, ceil
+from math import trunc, floor, ceil, radians
 from urbantz.utils import Coordinates
 
 
@@ -59,5 +59,30 @@ class TestCoordinates(TestCase):
     def test_ceil(self):
         self.assertTupleEqual(tuple(ceil(self.coords)), (13, -13))
 
+    def test_add(self):
+        other = Coordinates(lat=7.43, lng=-6.51)
+        self.assertEqual(self.coords + other, Coordinates(lat=20, lng=-20))
+        with self.assertRaises(TypeError):
+            self.coords + 4
+
+    def test_sub(self):
+        other = Coordinates(lat=2.57, lng=-3.49)
+        self.assertEqual(self.coords - other, Coordinates(lat=10, lng=-10))
+        with self.assertRaises(TypeError):
+            self.coords - "lol"
+
     def test_toJSON(self):
         self.assertListEqual(self.coords.toJSON(), [-13.49, 12.57])
+
+    def test_fromJSON(self):
+        self.assertEqual(Coordinates.fromJSON([-13.49, 12.57]), self.coords)
+
+    def test_to_radians(self):
+        self.assertTupleEqual(self.coords.to_radians(), (radians(12.57), radians(-13.49)))
+
+    def test_distance(self):
+        other = Coordinates(lat=2.57, lng=-3.49)
+        self.assertEqual(self.coords.distance(other), other.distance(self.coords))
+        self.assertEqual(self.coords.distance(other), 1564640.3229974532)
+        with self.assertRaises(NotImplementedError):
+            self.coords.distance("lol")
diff --git a/urbantz/utils.py b/urbantz/utils.py
index 49888d5..dfbb5af 100644
--- a/urbantz/utils.py
+++ b/urbantz/utils.py
@@ -42,7 +42,7 @@ class Coordinates(object):
             tuple(self) == tuple(other)
 
     def __add__(self, other):
-        if not hasattr(other, 'lat') or hasattr(other, 'lng'):
+        if not hasattr(other, 'lat') or not hasattr(other, 'lng'):
             return NotImplemented
         return self.__class__(
             lat=self.lat + other.lat,
@@ -50,7 +50,7 @@ class Coordinates(object):
         )
 
     def __sub__(self, other):
-        if not hasattr(other, 'lat') or hasattr(other, 'lng'):
+        if not hasattr(other, 'lat') or not hasattr(other, 'lng'):
             return NotImplemented
         return self.__class__(
             lat=self.lat - other.lat,