diff --git a/genrule/genrule.go b/genrule/genrule.go
index e5ee3fc..5a9376b 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -703,7 +703,7 @@
 	Shard_size *int64
 }
 
-const defaultShardSize = 100
+const defaultShardSize = 50
 
 func NewGenRule() *Module {
 	properties := &genRuleProperties{}