diff --git a/README.md b/README.md
index e600254..257ce61 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Usage:
   rbheap leak [flags] <dump-A> <dump-B> <dump-C>
 
 Flags:
-  -f, --format string   output format: "hex" / "full" (default "hex")
+  -f, --format string   output format: "hex" / "json" (default "hex")
   -h, --help            help for leak
   -v, --verbose         print verbose information
 ```
diff --git a/cmd/leak.go b/cmd/leak.go
index a89d478..c573bb9 100644
--- a/cmd/leak.go
+++ b/cmd/leak.go
@@ -38,7 +38,7 @@ objects are present in both B and C, and not present in A.`,
 		switch leakOpts.Format {
 		case "hex":
 			finder.PrintLeakedAddresses()
-		case "full":
+		case "json":
 			finder.PrintLeakedObjects()
 		default:
 			usage_er(
@@ -55,7 +55,7 @@ func init() {
 	leakCmd.PersistentFlags().StringVarP(
 		&leakOpts.Format,
 		"format", "f", "hex",
-		"output format: \"hex\" / \"full\"",
+		"output format: \"hex\" / \"json\"",
 	)
 
 	leakCmd.PersistentFlags().BoolVarP(