diff --git a/src/categories.js b/src/categories.js
index 95baee275e..61dbbfb82f 100644
--- a/src/categories.js
+++ b/src/categories.js
@@ -425,7 +425,8 @@ var RDB = require('./redis.js'),
 	};
 
 	Categories.addActiveUser = function(cid, uid) {
-		RDB.sadd('cid:' + cid + ':active_users', uid);
+		if(parseInt(uid, 10))
+			RDB.sadd('cid:' + cid + ':active_users', uid);
 	};
 
 	Categories.removeActiveUser = function(cid, uid) {
diff --git a/src/topics.js b/src/topics.js
index c95b3be200..1fd5dbc94b 100644
--- a/src/topics.js
+++ b/src/topics.js
@@ -336,7 +336,7 @@ var RDB = require('./redis.js'),
 					topicData.badgeclass = (topicInfo.hasread && current_user != 0) ? '' : 'badge-important';
 					topicData.teaser_text = topicInfo.teaserInfo.text || '',
 					topicData.teaser_username = topicInfo.teaserInfo.username || '';
-					topicData.teaser_userpicture = topicInfo.teaserInfo.picture || '';
+					topicData.teaser_userpicture = topicInfo.teaserInfo.picture || require('gravatar').url('', {}, https = nconf.get('https'));
 					topicData.teaser_pid = topicInfo.teaserInfo.pid;
 
 					topicData.teaser_timestamp = topicInfo.teaserInfo.timestamp ? (new Date(parseInt(topicInfo.teaserInfo.timestamp, 10)).toISOString()) : '';