diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 836b2daeab..c99c28bc0d 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -218,7 +218,6 @@ namespace ts {
             const _fs = require("fs");
             const _path = require("path");
             const _os = require("os");
-            const _tty = require("tty");
 
             // average async stat takes about 30 microseconds
             // set chunk size to do 30 files in < 1 millisecond
@@ -313,10 +312,6 @@ namespace ts {
             // time dynamically to match the large reference set?
             const watchedFileSet = createWatchedFileSet();
 
-            function isNode4OrLater(): Boolean {
-                return parseInt(process.version.charAt(1)) >= 4;
-            }
-
             const platform: string = _os.platform();
             // win32\win64 are case insensitive platforms, MacOS (darwin) by default is also case insensitive
             const useCaseSensitiveFileNames = platform !== "win32" && platform !== "win64" && platform !== "darwin";