diff --git a/pyproj/_crs.pyx b/pyproj/_crs.pyx
index 529b23c44..b536c61fc 100644
--- a/pyproj/_crs.pyx
+++ b/pyproj/_crs.pyx
@@ -198,6 +198,7 @@ cdef PJ * _from_name(
         PJ *
         """
         cdef PJ_TYPE[1] pj_types = [pj_type]
+        cdef char* c_auth_name = NULL
         if auth_name is not None:
             b_auth_name = cstrencode(auth_name)
             c_auth_name = b_auth_name
diff --git a/test/test_crs.py b/test/test_crs.py
index ea3518a63..5b13f81a0 100644
--- a/test/test_crs.py
+++ b/test/test_crs.py
@@ -833,10 +833,11 @@ def test_datum__from_name(input_name):
     assert dd.name == "World Geodetic System 1984"
 
 
-def test_datum_from_name__auth_type():
+@pytest.mark.parametrize("auth_name", [None, "ESRI"])
+def test_datum_from_name__auth_type(auth_name):
     dd = Datum.from_name(
         "WGS_1984_Geoid",
-        auth_name="ESRI",
+        auth_name=auth_name,
         datum_type=DatumType.VERTICAL_REFERENCE_FRAME,
     )
     assert dd.name == "WGS_1984_Geoid"