diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 41f782ed4f..928dd2cb9d 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -2211,11 +2211,11 @@ func MakeChain(ctx *cli.Context, stack *node.Node, readonly bool) (*core.BlockCh
 	vmcfg := vm.Config{EnablePreimageRecording: ctx.Bool(VMEnableDebugFlag.Name)}
 	if ctx.IsSet(VMTraceFlag.Name) {
 		if name := ctx.String(VMTraceFlag.Name); name != "" {
-			var config string
+			var config json.RawMessage
 			if ctx.IsSet(VMTraceConfigFlag.Name) {
-				config = ctx.String(VMTraceConfigFlag.Name)
+				config = json.RawMessage(ctx.String(VMTraceConfigFlag.Name))
 			}
-			t, err := live.Directory.New(name, json.RawMessage(config))
+			t, err := live.Directory.New(name, config)
 			if err != nil {
 				Fatalf("Failed to create tracer %q: %v", name, err)
 			}
diff --git a/eth/backend.go b/eth/backend.go
index 29af07cc56..746266cd10 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -208,7 +208,11 @@ func New(stack *node.Node, config *ethconfig.Config) (*Ethereum, error) {
 		}
 	)
 	if config.VMTrace != "" {
-		t, err := live.Directory.New(config.VMTrace, json.RawMessage(config.VMTraceConfig))
+		var traceConfig json.RawMessage
+		if config.VMTraceConfig != "" {
+			traceConfig = json.RawMessage(config.VMTraceConfig)
+		}
+		t, err := live.Directory.New(config.VMTrace, traceConfig)
 		if err != nil {
 			return nil, fmt.Errorf("Failed to create tracer %s: %v", config.VMTrace, err)
 		}