diff --git a/scanner/scanner/cache.py b/scanner/scanner/cache.py
index b21a9851..0f02447d 100644
--- a/scanner/scanner/cache.py
+++ b/scanner/scanner/cache.py
@@ -5,7 +5,7 @@ from typing import Any, Optional, Tuple
 
 type Cache = dict[Any, Tuple[Optional[asyncio.Event], Optional[datetime], Any]]
 
-def cache(ttl: timedelta, cache: Cache={}, typed=False):
+def cache(ttl: timedelta, cache: Optional[Cache] = None, typed=False):
 	"""
 	A cache decorator for async methods. If the same method is called twice with
 	the same args, the underlying method will only be called once and the first
@@ -17,6 +17,9 @@ def cache(ttl: timedelta, cache: Cache={}, typed=False):
 
 	"""
 
+	if cache is None:
+		cache = {}
+
 	def wrap(f):
 		@wraps(f)
 		async def wrapper(*args, **kwargs):