diff --git a/lib/iris/fileformats/netcdf.py b/lib/iris/fileformats/netcdf.py
index aaac902976..8e3d644633 100644
--- a/lib/iris/fileformats/netcdf.py
+++ b/lib/iris/fileformats/netcdf.py
@@ -708,7 +708,7 @@ def load_cubes(filenames, callback=None):
 def _bytes_if_ascii(string):
     """
     Convert the given string to a byte string (str in py2k, bytes in py3k)
-    iff the given string can be encoded to ascii, else maintain the type
+    if the given string can be encoded to ascii, else maintain the type
     of the inputted string.
 
     Note: passing objects without an `encode` method (such as None) will
@@ -1690,12 +1690,13 @@ def _create_cf_grid_mapping(self, cube, cf_var_cube):
             # Grid var not yet created?
             if cs not in self._coord_systems:
                 while cs.grid_mapping_name in self._dataset.variables:
-                    cs.grid_mapping_name = (
-                        self._increment_name(cs.grid_mapping_name))
+                    aname = self._increment_name(cs.grid_mapping_name)
+                    cs.grid_mapping_name = aname
 
                 cf_var_grid = self._dataset.createVariable(
                     cs.grid_mapping_name, np.int32)
-                cf_var_grid.grid_mapping_name = cs.grid_mapping_name
+                _setncattr(cf_var_grid, 'grid_mapping_name',
+                           cs.grid_mapping_name)
 
                 def add_ellipsoid(ellipsoid):
                     cf_var_grid.longitude_of_prime_meridian = (
diff --git a/lib/iris/tests/unit/fileformats/netcdf/test_Saver.py b/lib/iris/tests/unit/fileformats/netcdf/test_Saver.py
index 4486e9d609..91c9b9bbe1 100644
--- a/lib/iris/tests/unit/fileformats/netcdf/test_Saver.py
+++ b/lib/iris/tests/unit/fileformats/netcdf/test_Saver.py
@@ -505,19 +505,19 @@ def _grid_mapping_variable(self, coord_system):
 
         """
         cube = self._cube_with_cs(coord_system)
+
+        class NCMock(mock.Mock):
+            def setncattr(self, name, attr):
+                setattr(self, name, attr)
+
         # Calls the actual NetCDF saver with appropriate mocking, returning
         # the grid variable that gets created.
-        grid_variable = mock.Mock(name='NetCDFVariable')
+        grid_variable = NCMock(name='NetCDFVariable')
         create_var_fn = mock.Mock(side_effect=[grid_variable])
         dataset = mock.Mock(variables=[],
                             createVariable=create_var_fn)
         saver = mock.Mock(spec=Saver, _coord_systems=[],
                           _dataset=dataset)
-
-        class NCMock(mock.Mock):
-            def setncattr(self, name, attr):
-                setattr(self, name, attr)
-
         variable = NCMock()
 
         # This is the method we're actually testing!
@@ -525,7 +525,7 @@ def setncattr(self, name, attr):
 
         self.assertEqual(create_var_fn.call_count, 1)
         self.assertEqual(variable.grid_mapping,
-                         str.encode(grid_variable.grid_mapping_name))
+                         grid_variable.grid_mapping_name)
         return grid_variable
 
     def _variable_attributes(self, coord_system):
@@ -552,7 +552,7 @@ def _test(self, coord_system, expected):
 
     def test_rotated_geog_cs(self):
         coord_system = RotatedGeogCS(37.5, 177.5, ellipsoid=GeogCS(6371229.0))
-        expected = {'grid_mapping_name': 'rotated_latitude_longitude',
+        expected = {'grid_mapping_name': b'rotated_latitude_longitude',
                     'north_pole_grid_longitude': 0.0,
                     'grid_north_pole_longitude': 177.5,
                     'grid_north_pole_latitude': 37.5,
@@ -563,7 +563,7 @@ def test_rotated_geog_cs(self):
 
     def test_spherical_geog_cs(self):
         coord_system = GeogCS(6371229.0)
-        expected = {'grid_mapping_name': 'latitude_longitude',
+        expected = {'grid_mapping_name': b'latitude_longitude',
                     'longitude_of_prime_meridian': 0.0,
                     'earth_radius': 6371229.0
                     }
@@ -571,7 +571,7 @@ def test_spherical_geog_cs(self):
 
     def test_elliptic_geog_cs(self):
         coord_system = GeogCS(637, 600)
-        expected = {'grid_mapping_name': 'latitude_longitude',
+        expected = {'grid_mapping_name': b'latitude_longitude',
                     'longitude_of_prime_meridian': 0.0,
                     'semi_minor_axis': 600.0,
                     'semi_major_axis': 637.0,
@@ -583,7 +583,7 @@ def test_lambert_conformal(self):
                                         false_easting=-2, false_northing=-5,
                                         secant_latitudes=(38, 50),
                                         ellipsoid=GeogCS(6371000))
-        expected = {'grid_mapping_name': 'lambert_conformal_conic',
+        expected = {'grid_mapping_name': b'lambert_conformal_conic',
                     'latitude_of_projection_origin': 44,
                     'longitude_of_central_meridian': 2,
                     'false_easting': -2, 'false_northing': -5,
@@ -600,7 +600,7 @@ def test_laea_cs(self):
             false_easting=100,
             false_northing=200,
             ellipsoid=GeogCS(6377563.396, 6356256.909))
-        expected = {'grid_mapping_name': 'lambert_azimuthal_equal_area',
+        expected = {'grid_mapping_name': b'lambert_azimuthal_equal_area',
                     'latitude_of_projection_origin': 52,
                     'longitude_of_projection_origin': 10,
                     'false_easting': 100,