diff --git a/cmd/geth/config.go b/cmd/geth/config.go
index 26eeccb8b..d7b8b55d1 100644
--- a/cmd/geth/config.go
+++ b/cmd/geth/config.go
@@ -160,7 +160,7 @@ func makeFullNode(ctx *cli.Context) (*node.Node, ethapi.Backend) {
 		cfg.Eth.OverrideArrowGlacier = new(big.Int).SetUint64(ctx.GlobalUint64(utils.OverrideArrowGlacierFlag.Name))
 	}
 	if ctx.GlobalIsSet(utils.OverrideTerminalTotalDifficulty.Name) {
-		cfg.Eth.OverrideTerminalTotalDifficulty = new(big.Int).SetUint64(ctx.GlobalUint64(utils.OverrideTerminalTotalDifficulty.Name))
+		cfg.Eth.OverrideTerminalTotalDifficulty = utils.GlobalBig(ctx, utils.OverrideTerminalTotalDifficulty.Name)
 	}
 	backend, eth := utils.RegisterEthService(stack, &cfg.Eth)
 	// Warn users to migrate if they have a legacy freezer format.
diff --git a/cmd/utils/customflags.go b/cmd/utils/customflags.go
index 0a72e8034..e5be085a5 100644
--- a/cmd/utils/customflags.go
+++ b/cmd/utils/customflags.go
@@ -154,11 +154,11 @@ func (b *bigValue) String() string {
 }
 
 func (b *bigValue) Set(s string) error {
-	int, ok := math.ParseBig256(s)
+	intVal, ok := math.ParseBig256(s)
 	if !ok {
 		return errors.New("invalid integer syntax")
 	}
-	*b = (bigValue)(*int)
+	*b = (bigValue)(*intVal)
 	return nil
 }
 
@@ -172,6 +172,7 @@ func (f BigFlag) String() string {
 
 func (f BigFlag) Apply(set *flag.FlagSet) {
 	eachName(f.Name, func(name string) {
+		f.Value = new(big.Int)
 		set.Var((*bigValue)(f.Value), f.Name, f.Usage)
 	})
 }
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index ae1e77675..1fb489732 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -258,7 +258,7 @@ var (
 		Name:  "override.arrowglacier",
 		Usage: "Manually specify Arrow Glacier fork-block, overriding the bundled setting",
 	}
-	OverrideTerminalTotalDifficulty = cli.Uint64Flag{
+	OverrideTerminalTotalDifficulty = BigFlag{
 		Name:  "override.terminaltotaldifficulty",
 		Usage: "Manually specify TerminalTotalDifficulty, overriding the bundled setting",
 	}