diff --git a/src/json/ser.rs b/src/json/ser.rs
index 331fbe4a..23086cbd 100644
--- a/src/json/ser.rs
+++ b/src/json/ser.rs
@@ -1,5 +1,5 @@
 use std::io;
-use std::num::{Float, FpCategory};
+use std::num::FpCategory;
 use std::string::FromUtf8Error;
 
 use ser;