diff --git a/ffi/src/lib.rs b/ffi/src/lib.rs
index 7e8eaa49..a665b25a 100644
--- a/ffi/src/lib.rs
+++ b/ffi/src/lib.rs
@@ -67,9 +67,12 @@
 //! propogation. These types have implemented [From](std::convert::From) such that conversion from the Rust type
 //! to the C type is as painless as possible.
 
+extern crate core;
 extern crate libc;
 extern crate mentat;
 
+use core::fmt::Display;
+
 use std::collections::{
     BTreeSet,
 };
@@ -204,7 +207,7 @@ pub struct ExternResult {
     pub err: *const c_char,
 }
 
-impl<T, E> From<Result<T, E>> for ExternResult where E: std::error::Error {
+impl<T, E> From<Result<T, E>> for ExternResult where E: Display {
     fn from(result: Result<T, E>) -> Self {
         match result {
             Ok(value) => {
diff --git a/tools/cli/src/mentat_cli/errors.rs b/tools/cli/src/mentat_cli/errors.rs
deleted file mode 100644
index 0012c319..00000000
--- a/tools/cli/src/mentat_cli/errors.rs
+++ /dev/null
@@ -1,37 +0,0 @@
-// Copyright 2016 Mozilla
-//
-// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
-// this file except in compliance with the License. You may obtain a copy of the
-// License at http://www.apache.org/licenses/LICENSE-2.0
-// Unless required by applicable law or agreed to in writing, software distributed
-// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-// CONDITIONS OF ANY KIND, either express or implied. See the License for the
-// specific language governing permissions and limitations under the License.
-
-#![allow(dead_code)]
-
-use rusqlite;
-
-use mentat::errors as mentat;
-
-error_chain! {
-    types {
-        Error, ErrorKind, ResultExt, Result;
-    }
-
-    foreign_links {
-        Rusqlite(rusqlite::Error);
-        IoError(::std::io::Error);
-    }
-
-    links {
-        MentatError(mentat::Error, mentat::ErrorKind);
-    }
-
-    errors {
-        CommandParse(message: String) {
-            description("An error occured parsing the entered command")
-            display("{}", message)
-        }
-    }
-}