diff --git a/Modules/functions.c b/Modules/functions.c
index f7d9cf37..72d83513 100644
--- a/Modules/functions.c
+++ b/Modules/functions.c
@@ -100,6 +100,11 @@ l_ldap_str2dn(PyObject *unused, PyObject *args)
      */
     if (!PyArg_ParseTuple(args, "z#|i:str2dn", &str.bv_val, &str_len, &flags))
         return NULL;
+
+    if (str_len == 0) {
+        // GH-549: ldap_bv2dn() does not support empty string.
+        return PyList_New(0);
+    }
     str.bv_len = (ber_len_t) str_len;
 
     res = ldap_bv2dn(&str, &dn, flags);
diff --git a/Tests/t_cext.py b/Tests/t_cext.py
index 33fbf29a..9df16dc8 100644
--- a/Tests/t_cext.py
+++ b/Tests/t_cext.py
@@ -955,6 +955,12 @@ def test_require_san(self):
             _ldap.OPT_X_TLS_TRY
         )
 
+    def test_str2dn(self):
+        self.assertEqual(_ldap.str2dn(""), [])
+        self.assertEqual(_ldap.str2dn(None), [])
+        with self.assertRaises(TypeError):
+            _ldap.str2dn(object)
+
 
 if __name__ == '__main__':
     unittest.main()