diff --git a/django/contrib/gis/db/models/fields.py b/django/contrib/gis/db/models/fields.py
index 2daf08147b..9986fc5036 100644
--- a/django/contrib/gis/db/models/fields.py
+++ b/django/contrib/gis/db/models/fields.py
@@ -51,7 +51,7 @@ class GeometryField(Field):
     form_class = forms.GeometryField
 
     # Geodetic units.
-    geodetic_units = ('Decimal Degree', 'degree')
+    geodetic_units = ('decimal degree', 'degree')
 
     description = _("The base GIS field -- maps to the OpenGIS Specification Geometry type.")
 
@@ -147,7 +147,7 @@ class GeometryField(Field):
         Returns true if this field's SRID corresponds with a coordinate
         system that uses non-projected units (e.g., latitude/longitude).
         """
-        return self.units_name(connection) in self.geodetic_units
+        return self.units_name(connection).lower() in self.geodetic_units
 
     def get_distance(self, value, lookup_type, connection):
         """
diff --git a/django/contrib/gis/db/models/query.py b/django/contrib/gis/db/models/query.py
index 66b96a0873..b368f425be 100644
--- a/django/contrib/gis/db/models/query.py
+++ b/django/contrib/gis/db/models/query.py
@@ -646,7 +646,7 @@ class GeoQuerySet(QuerySet):
             # been transformed via the `transform` GeoQuerySet method.
             if self.query.transformed_srid:
                 u, unit_name, s = get_srid_info(self.query.transformed_srid, connection)
-                geodetic = unit_name in geo_field.geodetic_units
+                geodetic = unit_name.lower() in geo_field.geodetic_units
 
             if backend.spatialite and geodetic:
                 raise ValueError('SQLite does not support linear distance calculations on geodetic coordinate systems.')