diff --git a/PENDING.md b/PENDING.md
index 4d87301f0d5b..2de586cfb470 100644
--- a/PENDING.md
+++ b/PENDING.md
@@ -31,6 +31,7 @@ IMPROVEMENTS
 * Gaia REST API (`gaiacli advanced rest-server`)
 
 * Gaia CLI  (`gaiacli`)
+  * [\#2749](https://github.com/cosmos/cosmos-sdk/pull/2749) Add --chain-id flag to gaiad testnet
 
 * Gaia
 
diff --git a/cmd/gaia/init/testnet.go b/cmd/gaia/init/testnet.go
index 8bada583e22f..8ca274f78bab 100644
--- a/cmd/gaia/init/testnet.go
+++ b/cmd/gaia/init/testnet.go
@@ -75,14 +75,20 @@ Example:
 	cmd.Flags().String(flagStartingIPAddress, "192.168.0.1",
 		"Starting IP address (192.168.0.1 results in persistent peers list ID0@192.168.0.1:46656, ID1@192.168.0.2:46656, ...)")
 
+	cmd.Flags().String(client.FlagChainID, "", "genesis file chain-id, if left blank will be randomly created")
+
 	return cmd
 }
 
 func initTestnet(config *cfg.Config, cdc *codec.Codec) error {
+	var chainID string
 	outDir := viper.GetString(flagOutputDir)
 	numValidators := viper.GetInt(flagNumValidators)
 
-	chainID := "chain-" + cmn.RandStr(6)
+	chainID = viper.GetString(client.FlagChainID)
+	if chainID == "" {
+		chainID = "chain-" + cmn.RandStr(6)
+	}
 
 	monikers := make([]string, numValidators)
 	nodeIDs := make([]string, numValidators)