diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 2d6bb4f5bd..f86fc37f50 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -881,6 +881,13 @@ func MakeChainConfigFromDb(ctx *cli.Context, db ethdb.Database) *params.ChainCon
 				config.EIP158Block = params.MainNetSpuriousDragon
 			}
 		}
+		if config.ChainId.BitLen() == 0 {
+			if ctx.GlobalBool(TestNetFlag.Name) {
+				config.ChainId = params.TestNetChainID
+			} else {
+				config.ChainId = params.MainNetChainID
+			}
+		}
 		config.DAOForkSupport = true
 	}
 
diff --git a/params/util.go b/params/util.go
index 377f4ce7c9..b96f33da27 100644
--- a/params/util.go
+++ b/params/util.go
@@ -37,4 +37,7 @@ var (
 
 	TestNetSpuriousDragon = big.NewInt(3000000)
 	MainNetSpuriousDragon = big.NewInt(3000000)
+
+	TestNetChainID = big.NewInt(2) // Test net default chain ID
+	MainNetChainID = big.NewInt(1) // main net default chain ID
 )