diff --git a/src/server.c b/src/server.c
index e39ee4c74..aac39d983 100644
--- a/src/server.c
+++ b/src/server.c
@@ -864,18 +864,22 @@ void activeExpireCycle(int type) {
                 if ((de = dictGetRandomKey(db->expires)) == NULL) break;
                 ttl = dictGetSignedIntegerVal(de)-now;
                 if (activeExpireCycleTryExpire(db,de,now)) expired++;
-                if (ttl < 0) ttl = 0;
-                ttl_sum += ttl;
-                ttl_samples++;
+                if (ttl > 0) {
+                    /* We want the average TTL of keys yet not expired. */
+                    ttl_sum += ttl;
+                    ttl_samples++;
+                }
             }
 
             /* Update the average TTL stats for this database. */
             if (ttl_samples) {
                 long long avg_ttl = ttl_sum/ttl_samples;
 
+                /* Do a simple running average with a few samples.
+                 * We just use the current estimate with a weight of 2%
+                 * and the previous estimate with a weight of 98%. */
                 if (db->avg_ttl == 0) db->avg_ttl = avg_ttl;
-                /* Smooth the value averaging with the previous one. */
-                db->avg_ttl = (db->avg_ttl+avg_ttl)/2;
+                db->avg_ttl = (db->avg_ttl/50)*49 + (avg_ttl/50);
             }
 
             /* We can't block forever here even if there are many keys to