diff --git a/src/check_jsonschema/cachedownloader.py b/src/check_jsonschema/cachedownloader.py
index 6b9865126..40f1d2cbb 100644
--- a/src/check_jsonschema/cachedownloader.py
+++ b/src/check_jsonschema/cachedownloader.py
@@ -33,7 +33,7 @@ def _base_cache_dir() -> str | None:
     return cache_dir
 
 
-def _resolve_cache_dir(dirname: str = "downloads") -> str | None:
+def _resolve_cache_dir(dirname: str) -> str | None:
     cache_dir = _base_cache_dir()
     if cache_dir:
         cache_dir = os.path.join(cache_dir, "check_jsonschema", dirname)
@@ -100,13 +100,8 @@ class FailedDownloadError(Exception):
 
 
 class CacheDownloader:
-    def __init__(
-        self, cache_dir: str | None = None, disable_cache: bool = False
-    ) -> None:
-        if cache_dir is None:
-            self._cache_dir = _resolve_cache_dir()
-        else:
-            self._cache_dir = _resolve_cache_dir(cache_dir)
+    def __init__(self, cache_dir: str, *, disable_cache: bool = False) -> None:
+        self._cache_dir = _resolve_cache_dir(cache_dir)
         self._disable_cache = disable_cache
 
     def _download(
diff --git a/src/check_jsonschema/schema_loader/readers.py b/src/check_jsonschema/schema_loader/readers.py
index 65280808b..f496d42eb 100644
--- a/src/check_jsonschema/schema_loader/readers.py
+++ b/src/check_jsonschema/schema_loader/readers.py
@@ -79,7 +79,7 @@ def __init__(
         self.url = url
         self.parsers = ParserSet()
         self.downloader = CacheDownloader(
-            disable_cache=disable_cache,
+            "downloads", disable_cache=disable_cache
         ).bind(url, cache_filename, validation_callback=self._parse)
         self._parsed_schema: dict | _UnsetType = _UNSET
 
diff --git a/src/check_jsonschema/schema_loader/resolver.py b/src/check_jsonschema/schema_loader/resolver.py
index 5084328a5..a82ae31c9 100644
--- a/src/check_jsonschema/schema_loader/resolver.py
+++ b/src/check_jsonschema/schema_loader/resolver.py
@@ -66,7 +66,7 @@ def create_retrieve_callable(
         base_uri = retrieval_uri
 
     cache = ResourceCache()
-    downloader = CacheDownloader("refs", disable_cache)
+    downloader = CacheDownloader("refs", disable_cache=disable_cache)
 
     def get_local_file(uri: str) -> t.Any:
         path = filename2path(uri)
diff --git a/tests/unit/test_cachedownloader.py b/tests/unit/test_cachedownloader.py
index 30d47052b..99382e921 100644
--- a/tests/unit/test_cachedownloader.py
+++ b/tests/unit/test_cachedownloader.py
@@ -30,7 +30,7 @@ def default_response():
 
 
 def test_default_filename_from_uri(default_response):
-    cd = CacheDownloader().bind("https://example.com/schema1.json")
+    cd = CacheDownloader("downloads").bind("https://example.com/schema1.json")
     assert cd._filename == "schema1.json"
 
 
@@ -76,7 +76,7 @@ def fake_expanduser(path):
     monkeypatch.setattr(platform, "system", fakesystem)
     monkeypatch.setattr(os.path, "expanduser", fake_expanduser)
 
-    cd = CacheDownloader()
+    cd = CacheDownloader("downloads")
     assert cd._cache_dir == expect_value
 
     if sysname == "Darwin":
@@ -114,7 +114,7 @@ def test_cachedownloader_cached_file(tmp_path, monkeypatch, default_response):
     f.write_text("{}")
 
     # set the cache_dir to the tmp dir (so that cache_dir will always be set)
-    cd = CacheDownloader(cache_dir=tmp_path).bind(str(f))
+    cd = CacheDownloader(tmp_path).bind(str(f))
     # patch the downloader to skip any download "work"
     monkeypatch.setattr(
         cd._downloader, "_download", lambda file_uri, filename, response_ok: str(f)
@@ -128,7 +128,7 @@ def test_cachedownloader_cached_file(tmp_path, monkeypatch, default_response):
 def test_cachedownloader_on_success(get_download_cache_loc, disable_cache):
     add_default_response()
     f = get_download_cache_loc("schema1.json")
-    cd = CacheDownloader(disable_cache=disable_cache).bind(
+    cd = CacheDownloader("downloads", disable_cache=disable_cache).bind(
         "https://example.com/schema1.json"
     )
 
@@ -171,7 +171,7 @@ def test_cachedownloader_succeeds_after_few_errors(
         )
     add_default_response()
     f = get_download_cache_loc("schema1.json")
-    cd = CacheDownloader(disable_cache=disable_cache).bind(
+    cd = CacheDownloader("downloads", disable_cache=disable_cache).bind(
         "https://example.com/schema1.json"
     )
 
@@ -205,7 +205,7 @@ def test_cachedownloader_fails_after_many_errors(
             )
     add_default_response()  # never reached, the 11th response
     f = get_download_cache_loc("schema1.json")
-    cd = CacheDownloader(disable_cache=disable_cache).bind(
+    cd = CacheDownloader("downloads", disable_cache=disable_cache).bind(
         "https://example.com/schema1.json"
     )
     with pytest.raises(FailedDownloadError):
@@ -226,6 +226,7 @@ def test_cachedownloader_retries_on_bad_data(get_download_cache_loc, disable_cac
     add_default_response()
     f = get_download_cache_loc("schema1.json")
     cd = CacheDownloader(
+        "downloads",
         disable_cache=disable_cache,
     ).bind(
         "https://example.com/schema1.json",
@@ -281,7 +282,7 @@ def fake_mktime(*args):
     if file_exists:
         inject_cached_download(uri, original_file_contents)
 
-    cd = CacheDownloader().bind(uri)
+    cd = CacheDownloader("downloads").bind(uri)
 
     # if the file already existed, it will not be overwritten by the cachedownloader
     # so the returned value for both the downloader and a direct file read should be the
@@ -326,7 +327,7 @@ def dummy_validate_bytes(data):
 
     # construct a downloader pointed at the schema and file, expecting a cache hit
     # and use the above validation method
-    cd = CacheDownloader().bind(
+    cd = CacheDownloader("downloads").bind(
         "https://example.com/schema1.json",
         validation_callback=dummy_validate_bytes,
     )