diff --git a/et_cache/cacheHandler.go b/et_cache/cacheHandler.go
index 8eca1bc..6f9a46c 100644
--- a/et_cache/cacheHandler.go
+++ b/et_cache/cacheHandler.go
@@ -78,7 +78,7 @@ func (the *CacheHandler) enqueue(p *common_models.ProcessData) *common_models.Pr
 }
 
 func (the *CacheHandler) windowCalc(raw float64, window common_models.CacheWindow) (float64, bool) {
-	if window.Size() == 0 {
+	if window.Size() == 0 || window.Len() == 0 {
 		return raw, false
 	}
 	result := 0.0