diff --git a/django/contrib/gis/gdal/raster/source.py b/django/contrib/gis/gdal/raster/source.py
index cb7b4cf3ac..03fa1f8f22 100644
--- a/django/contrib/gis/gdal/raster/source.py
+++ b/django/contrib/gis/gdal/raster/source.py
@@ -250,7 +250,7 @@ class GDALRaster(GDALBase):
     @geotransform.setter
     def geotransform(self, values):
         "Set the geotransform for the data source."
-        if sum([isinstance(x, (int, float)) for x in values]) != 6:
+        if len(values) != 6 or not all(isinstance(x, (int, float)) for x in values):
             raise ValueError('Geotransform must consist of 6 numeric values.')
         # Create ctypes double array with input and write data
         values = (c_double * 6)(*values)
diff --git a/tests/gis_tests/gdal_tests/test_raster.py b/tests/gis_tests/gdal_tests/test_raster.py
index 9e23d78c68..5495178a13 100644
--- a/tests/gis_tests/gdal_tests/test_raster.py
+++ b/tests/gis_tests/gdal_tests/test_raster.py
@@ -103,6 +103,9 @@ class GDALRasterTests(SimpleTestCase):
         self.assertEqual(self.rs.skew.y, 0)
         # Create in-memory rasters and change gtvalues
         rsmem = GDALRaster(JSON_RASTER)
+        # geotransform accepts both floats and ints
+        rsmem.geotransform = [0.0, 1.0, 2.0, 3.0, 4.0, 5.0]
+        self.assertEqual(rsmem.geotransform, [0.0, 1.0, 2.0, 3.0, 4.0, 5.0])
         rsmem.geotransform = range(6)
         self.assertEqual(rsmem.geotransform, [float(x) for x in range(6)])
         self.assertEqual(rsmem.origin, [0, 3])
@@ -117,6 +120,18 @@ class GDALRasterTests(SimpleTestCase):
         self.assertEqual(rsmem.width, 5)
         self.assertEqual(rsmem.height, 5)
 
+    def test_geotransform_bad_inputs(self):
+        rsmem = GDALRaster(JSON_RASTER)
+        error_geotransforms = [
+            [1, 2],
+            [1, 2, 3, 4, 5, 'foo'],
+            [1, 2, 3, 4, 5, 6, 'foo'],
+        ]
+        msg = 'Geotransform must consist of 6 numeric values.'
+        for geotransform in error_geotransforms:
+            with self.subTest(i=geotransform), self.assertRaisesMessage(ValueError, msg):
+                rsmem.geotransform = geotransform
+
     def test_rs_extent(self):
         self.assertEqual(
             self.rs.extent,