diff --git a/README.md b/README.md
index d5ead64..327d234 100644
--- a/README.md
+++ b/README.md
@@ -522,7 +522,7 @@ request format:
   "sound": {
     "critical": 1,
     "name": "default",
-    "volume": volume
+    "volume": 2.0
   }
 }
 ```