diff --git a/doc/source/whatsnew/v0.20.0.txt b/doc/source/whatsnew/v0.20.0.txt
index c94429b469641..184733da787af 100644
--- a/doc/source/whatsnew/v0.20.0.txt
+++ b/doc/source/whatsnew/v0.20.0.txt
@@ -632,3 +632,5 @@ Bug Fixes
 - Bug in ``pd.melt()`` where passing a tuple value for ``value_vars`` caused a ``TypeError`` (:issue:`15348`)
 - Bug in ``.eval()`` which caused multiline evals to fail with local variables not on the first line (:issue:`15342`)
 - Bug in ``pd.read_msgpack`` which did not allow to load dataframe with an index of type ``CategoricalIndex`` (:issue:`15487`)
+
+- Bug in ``nanops.py`` due to bottleneck, which produces overflow in nansum on Windows (:issue:`15453`)
diff --git a/pandas/core/nanops.py b/pandas/core/nanops.py
index 0cc3a2d039b5e..151cbd0dd6032 100644
--- a/pandas/core/nanops.py
+++ b/pandas/core/nanops.py
@@ -128,8 +128,7 @@ def _bn_ok_dtype(dt, name):
         # bottleneck does not properly upcast during the sum
         # so can overflow
         if name == 'nansum':
-            if dt.itemsize < 8:
-                return False
+            return False
 
         return True
     return False
diff --git a/pandas/tests/test_nanops.py b/pandas/tests/test_nanops.py
index 937c20d009b6b..f1c64ca96a80c 100644
--- a/pandas/tests/test_nanops.py
+++ b/pandas/tests/test_nanops.py
@@ -327,6 +327,12 @@ def test_nansum(self):
         self.check_funs(nanops.nansum, np.sum, allow_str=False,
                         allow_date=False, allow_tdelta=True, check_dtype=False)
 
+    def test_nansum_overflow(self):
+        s = Series([2**31])
+        self.assertEqual(s.sum(), 2147483648)
+        s = Series([2**31 - 1, 1])
+        self.assertEqual(s.sum(), 2147483648)
+
     def test_nanmean(self):
         self.check_funs(nanops.nanmean, np.mean, allow_complex=False,
                         allow_obj=False, allow_str=False, allow_date=False,