diff --git a/src/rpn.rs b/src/rpn.rs
index 8ccf5d6..2bfbbf5 100644
--- a/src/rpn.rs
+++ b/src/rpn.rs
@@ -52,10 +52,8 @@ use std::{
 
 use CalcType::*;
 
-extern crate strerror;
 extern crate sysexits;
 
-use strerror::c_error;
 use sysexits::EX_DATAERR;
 
 #[derive(Clone, PartialEq, PartialOrd, Debug)]