diff --git a/chain/sync_test.go b/chain/sync_test.go
index 18520a07f..f4f553df3 100644
--- a/chain/sync_test.go
+++ b/chain/sync_test.go
@@ -45,6 +45,11 @@ func init() {
 	policy.SetSupportedProofTypes(abi.RegisteredSealProof_StackedDrg2KiBV1)
 	policy.SetConsensusMinerMinPower(abi.NewStoragePower(2048))
 	policy.SetMinVerifiedDealSize(abi.NewStoragePower(256))
+
+	// these tests assume really fast block times. disabling
+	// the consistent broadcast delay to avoid them from adding
+	// an unnecessary overhead.
+	build.CBDeliveryDelay = 2 * time.Millisecond
 }
 
 const source = 0