diff --git a/idx/cassandra/cassandra.go b/idx/cassandra/cassandra.go
index <HASH>..<HASH> 100644
--- a/idx/cassandra/cassandra.go
+++ b/idx/cassandra/cassandra.go
@@ -227,7 +227,7 @@ func (c *CasIdx) AddOrUpdate(data *schema.MetricData, partition int32) error {
 
 	if inMemory {
 		if existing.Partition == partition {
-			oldest := time.Now().Add(-1 * updateInterval).Add(-1 * time.Duration(rand.Int63n(updateInterval.Nanoseconds()*int64(updateFuzzyness*100))))
+			oldest := time.Now().Add(-1 * updateInterval).Add(-1 * time.Duration(rand.Int63n(updateInterval.Nanoseconds()*int64(updateFuzzyness*100)/100)))
 			if existing.LastUpdate < oldest.Unix() {
 				log.Debug("cassandra-idx def hasn't been seen for a while, updating index.")
 				def := schema.MetricDefinitionFromMetricData(data)
fix metricDef fuzzy formula

due to the multiplication by <I>, it was subtracting way too much,
so that metricdefs are less likely to be updated.
However the multiplication is good to turn the float value into a useful
factor, but then we have to divide again to compensate.

With this fix applied, we will update the metricdef more frequently like
we were supposed to.