diff --git a/dvc/repo/ls_url.py b/dvc/repo/ls_url.py
index f237bc3e7..ede671835 100644
--- a/dvc/repo/ls_url.py
+++ b/dvc/repo/ls_url.py
@@ -10,7 +10,7 @@ def parse_external_url(url, config=None):
     return fs, fs_path
 
 
-def ls_url(url, config=None, recursive=False):
+def ls_url(url, *, config=None, recursive=False):
     fs, fs_path = parse_external_url(url, config=config)
     try:
         info = fs.info(fs_path)
diff --git a/dvc/testing/workspace_tests.py b/dvc/testing/workspace_tests.py
index 715ffb556..42477c7fd 100644
--- a/dvc/testing/workspace_tests.py
+++ b/dvc/testing/workspace_tests.py
@@ -154,7 +154,7 @@ class TestLsUrl:
     def test_file(self, cloud, fname):
         cloud.gen({fname: "foo contents"})
         fs, fs_path = parse_external_url(cloud.url, cloud.config)
-        result = ls_url(str(cloud / fname), cloud.config)
+        result = ls_url(str(cloud / fname), config=cloud.config)
         match_files(
             fs,
             result,
@@ -166,7 +166,7 @@ class TestLsUrl:
             {"dir/foo": "foo contents", "dir/subdir/bar": "bar contents"}
         )
         fs, _ = parse_external_url(cloud.url, cloud.config)
-        result = ls_url(str(cloud / "dir"), cloud.config)
+        result = ls_url(str(cloud / "dir"), config=cloud.config)
         match_files(
             fs,
             result,
@@ -181,7 +181,9 @@ class TestLsUrl:
             {"dir/foo": "foo contents", "dir/subdir/bar": "bar contents"}
         )
         fs, _ = parse_external_url(cloud.url, cloud.config)
-        result = ls_url(str(cloud / "dir"), cloud.config, recursive=True)
+        result = ls_url(
+            str(cloud / "dir"), config=cloud.config, recursive=True
+        )
         match_files(
             fs,
             result,
@@ -193,4 +195,4 @@ class TestLsUrl:
 
     def test_nonexistent(self, cloud):
         with pytest.raises(URLMissingError):
-            ls_url(str(cloud / "dir"), cloud.config)
+            ls_url(str(cloud / "dir"), config=cloud.config)