diff --git a/checkpy/caches.py b/checkpy/caches.py
index 635ea05..4ff35bc 100644
--- a/checkpy/caches.py
+++ b/checkpy/caches.py
@@ -1,58 +1,42 @@
 import sys
+from functools import wraps
 
 _caches = []
 
-class _Cache(object):
-	def __init__(self):
-		self._cache = {}
-		_caches.append(self)
 
-	def __setitem__(self, key, value):
-		self._cache[key] = value
+class _Cache(dict):
+	"""A dict() subclass that appends a self-reference to _caches"""
+	def __init__(self, *args, **kwargs):
+		super(_Cache, self).__init__(*args, **kwargs)
+		_caches.append(self)
 
-	def __getitem__(self, key):
-		return self._cache.get(key, None)
 
-	def __contains__(self, key):
-		return key in self._cache
+def cache(*keys):
+	"""cache decorator
 
-	def delete(self, key):
-		if key not in self._cache:
-			return False
-		del self._cache[key]
-		return True
+	Caches input and output of a function. If arguments are passed to
+	the decorator, take those as key for the cache. Otherwise use the
+	function arguments and sys.argv as key.
 
-	def clear(self):
-		self._cache.clear()
+	"""
+	def cacheWrapper(func):
+		localCache = _Cache()
 
-"""
-cache decorator
-Caches input and output of a function. If arguments are passed to
-the decorator, take those as key for the cache, otherwise the
-function arguments.
-"""
-def cache(*keys):
-	def cacheWrapper(func, localCache = _Cache()):
+		@wraps(func)
 		def cachedFuncWrapper(*args, **kwargs):
 			if keys:
-				key = keys
+				key = str(keys)
 			else:
-				# treat all collections in kwargs as tuples for hashing purposes
-				values = list(kwargs.values())
-				for i in range(len(values)):
-					try:
-						values[i] = tuple(values[i])
-					except TypeError:
-						pass
-				key = args + tuple(values) + tuple(sys.argv)
+				key = str(args) + str(kwargs) + str(sys.argv)
 
 			if key not in localCache:
 				localCache[key] = func(*args, **kwargs)
-				
 			return localCache[key]
 		return cachedFuncWrapper
+
 	return cacheWrapper
 
+
 def clearAllCaches():
 	for cache in _caches:
 		cache.clear()