diff --git a/r2/r2/controllers/api.py b/r2/r2/controllers/api.py
index 53aa13514..26d7552fd 100644
--- a/r2/r2/controllers/api.py
+++ b/r2/r2/controllers/api.py
@@ -241,6 +241,7 @@ class ApiController(RedditController):
         #update the modified flags
         set_last_modified(c.user, 'overview')
         set_last_modified(c.user, 'submitted')
+        set_last_modified(c.user, 'liked')
         
         # flag search indexer that something has changed
         tc.changed(l)
diff --git a/r2/r2/controllers/reddit_base.py b/r2/r2/controllers/reddit_base.py
index d2195a06f..597d36aa5 100644
--- a/r2/r2/controllers/reddit_base.py
+++ b/r2/r2/controllers/reddit_base.py
@@ -574,7 +574,7 @@ class RedditController(BaseController):
             return
 
         date = utils.is_modified_since(thing, action, request.if_modified_since)
-        if date is True:
+        if date is False:
             abort(304, 'not modified')
         else:
             c.response.headers['Last-Modified'] = http_utils.http_date_str(date)
diff --git a/r2/r2/lib/utils/thing_utils.py b/r2/r2/lib/utils/thing_utils.py
index 62c9cdedb..bc89e6146 100644
--- a/r2/r2/lib/utils/thing_utils.py
+++ b/r2/r2/lib/utils/thing_utils.py
@@ -6,27 +6,30 @@ def make_last_modified():
     last_modified = last_modified.replace(microsecond = 0)
     return last_modified
 
+def last_modified_key(thing, action):
+    return 'last_' + action + '_' + thing._fullname
+
 def is_modified_since(thing, action, date):
     """Returns true if the date is older than the last_[action] date,
     which means a 304 should be returned. Otherwise returns the date
     that should be sent as the last-modified header."""
     from pylons import g
+    cache = g.permacache
 
-    prop = 'last_' + action
-    if not hasattr(thing, prop):
+    key = last_modified_key(thing, action)
+    last_modified = cache.get(key)
+    if not last_modified:
+        #if there is no last_modified, add one
         last_modified = make_last_modified()
-        setattr(thing, prop, last_modified)
-        thing._commit()
-    else:
-        last_modified = getattr(thing, prop)
+        cache.set(key, last_modified)
 
     if not date or date < last_modified:
         return last_modified
-    
-    #if a date was passed in and it's equal to last modified
-    return True
+    else:
+        #if a date was passed in and it's >= to last modified
+        return False
 
 def set_last_modified(thing, action):
     from pylons import g
-    setattr(thing, 'last_' + action, make_last_modified())
-    thing._commit()
+    key = last_modified_key(thing, action)
+    g.permacache.set(key, make_last_modified())