diff --git a/drf_spectacular/plumbing.py b/drf_spectacular/plumbing.py
index 879c4eb4..eb4799fb 100644
--- a/drf_spectacular/plumbing.py
+++ b/drf_spectacular/plumbing.py
@@ -1283,6 +1283,7 @@ def build_mock_request(method, path, view, original_request, **kwargs):
 
 def set_query_parameters(url, **kwargs) -> str:
     """ deconstruct url, safely attach query parameters in kwargs, and serialize again """
+    url = str(url)  # Force evaluation of reverse_lazy urls
     scheme, netloc, path, params, query, fragment = urllib.parse.urlparse(url)
     query = urllib.parse.parse_qs(query)
     query.update({k: v for k, v in kwargs.items() if v is not None})
@@ -1291,6 +1292,7 @@ def set_query_parameters(url, **kwargs) -> str:
 
 
 def get_relative_url(url: str) -> str:
+    url = str(url)  # Force evaluation of reverse_lazy urls
     scheme, netloc, path, params, query, fragment = urllib.parse.urlparse(url)
     return urllib.parse.urlunparse(('', '', path, params, query, fragment))
 
diff --git a/tests/test_plumbing.py b/tests/test_plumbing.py
index cbdafcfe..b1bdc63e 100644
--- a/tests/test_plumbing.py
+++ b/tests/test_plumbing.py
@@ -16,13 +16,14 @@
 from django.conf.urls import include
 from django.db import models
 from django.urls import re_path
+from django.utils.functional import lazystr
 from rest_framework import generics, serializers
 
 from drf_spectacular.openapi import AutoSchema
 from drf_spectacular.plumbing import (
     analyze_named_regex_pattern, build_basic_type, build_choice_field, detype_pattern,
-    follow_field_source, force_instance, get_list_serializer, is_field, is_serializer,
-    resolve_type_hint, safe_ref,
+    follow_field_source, force_instance, get_list_serializer, get_relative_url, is_field,
+    is_serializer, resolve_type_hint, safe_ref, set_query_parameters,
 )
 from drf_spectacular.validation import validate_schema
 from tests import generate_schema
@@ -437,3 +438,13 @@ def test_safe_ref():
     schema = safe_ref(schema)
     assert schema == {'$ref': '#/components/schemas/Foo'}
     assert safe_ref(schema) == safe_ref(schema)
+
+
+def test_url_tooling_with_lazy_url():
+    some_url = "http://api.example.org/accounts/"
+
+    assert get_relative_url(some_url) == "/accounts/"
+    assert set_query_parameters(some_url, foo=123) == some_url + "?foo=123"
+
+    assert get_relative_url(lazystr(some_url)) == "/accounts/"
+    assert set_query_parameters(lazystr(some_url), foo=123) == some_url + "?foo=123"