diff -r caf3ceb93307 Lib/test/test_functools.py
--- a/Lib/test/test_functools.py	Wed Nov 09 23:51:54 2016 +0200
+++ b/Lib/test/test_functools.py	Wed Nov 09 18:46:33 2016 -0500
@@ -1189,6 +1189,21 @@
         self.assertEqual(misses, 4)
         self.assertEqual(currsize, 2)
 
+    def test_lru_type_error(self):
+        @functools.lru_cache(maxsize=None)
+        def infinite_cache(o):
+            pass
+
+        @functools.lru_cache(maxsize=10)
+        def limited_cache(o):
+            pass
+
+        with self.assertRaises(TypeError):
+            infinite_cache([])
+
+        with self.assertRaises(TypeError):
+            limited_cache([])
+
     def test_lru_with_maxsize_none(self):
         @self.module.lru_cache(maxsize=None)
         def fib(n):
diff -r caf3ceb93307 Modules/_functoolsmodule.c
--- a/Modules/_functoolsmodule.c	Wed Nov 09 23:51:54 2016 +0200
+++ b/Modules/_functoolsmodule.c	Wed Nov 09 18:46:33 2016 -0500
@@ -793,8 +793,10 @@
     if (!key)
         return NULL;
     hash = PyObject_Hash(key);
-    if (hash == -1)
+    if (hash == -1) {
+        Py_DECREF(key);
         return NULL;
+    }
     result = _PyDict_GetItem_KnownHash(self->cache, key, hash);
     if (result) {
         Py_INCREF(result);
@@ -849,8 +851,10 @@
     if (!key)
         return NULL;
     hash = PyObject_Hash(key);
-    if (hash == -1)
+    if (hash == -1) {
+        Py_DECREF(key);
         return NULL;
+    }
     link  = (lru_list_elem *)_PyDict_GetItem_KnownHash(self->cache, key, hash);
     if (link) {
         lru_cache_extricate_link(link);