diff --git a/scrapy/trunk/scrapy/conf/core_settings.py b/scrapy/trunk/scrapy/conf/core_settings.py
index 70da5c802..ad140af03 100644
--- a/scrapy/trunk/scrapy/conf/core_settings.py
+++ b/scrapy/trunk/scrapy/conf/core_settings.py
@@ -11,7 +11,7 @@ USER_AGENT = '%s/%s' % (BOT_NAME, BOT_VERSION)
 DOWNLOAD_TIMEOUT = 180      # 3mins
 CONCURRENT_DOMAINS = 8    # number of domains to scrape in parallel
 REQUESTS_PER_DOMAIN = 8     # max simultaneous requests per domain
-CACHE2_EXPIRATION_SECS = 48 * 60 * 60 # seconds while cached response is still valid
+CACHE2_EXPIRATION_SECS = 48 * 60 * 60 # seconds while cached response is still valid (a negative value means "never expires")
 
 LOG_ENABLED = True  #
 LOGLEVEL = 'DEBUG'   # default loglevel
diff --git a/scrapy/trunk/scrapy/contrib/downloadermiddleware/cache.py b/scrapy/trunk/scrapy/contrib/downloadermiddleware/cache.py
index a97f7dae8..356c51127 100644
--- a/scrapy/trunk/scrapy/contrib/downloadermiddleware/cache.py
+++ b/scrapy/trunk/scrapy/contrib/downloadermiddleware/cache.py
@@ -1,6 +1,7 @@
 from __future__ import with_statement
 
 import os
+import sys
 import hashlib
 import datetime
 import urlparse
@@ -33,7 +34,11 @@ class CacheMiddleware(object):
 
         key = request.fingerprint()
         domain = spider.domain_name
-        response = self.cache.retrieve_response(domain, key)
+        try:
+            response = self.cache.retrieve_response(domain, key)
+        except:
+            log.msg("Corrupt cache for %s" % request.url, log.WARNING)
+            response = False
         if response:
             response.cached = True
             if not 200 <= int(response.status) < 300:
@@ -115,11 +120,16 @@ class Cache(object):
         if os.path.exists(requestpath):
             with open(os.path.join(requestpath, 'pickled_meta'), 'r') as f:
                 metadata = pickle.load(f)
-            if datetime.datetime.utcnow() <= metadata['timestamp'] + datetime.timedelta(seconds=settings.getint('CACHE2_EXPIRATION_SECS')):
-                return True
+            expiration_secs = settings.getint('CACHE2_EXPIRATION_SECS')
+            if expiration_secs >= 0:
+                if datetime.datetime.utcnow() <= metadata['timestamp'] + datetime.timedelta(seconds=expiration_secs):
+                    return True
+                else:
+                    log.msg('dropping old cached response from %s' % metadata['timestamp'])
+                    return False
             else:
-                log.msg('dropping old cached response from %s' % metadata['timestamp'])
-                return False
+                # disabled cache expiration
+                return True
         else:
             return False