diff --git a/src/rustfmt_diff.rs b/src/rustfmt_diff.rs
index 3e9fd913d7c6..3fb228653851 100644
--- a/src/rustfmt_diff.rs
+++ b/src/rustfmt_diff.rs
@@ -12,6 +12,7 @@ use diff;
 use std::collections::VecDeque;
 use std::io;
 use term;
+use utils::isatty;
 
 #[derive(Debug, PartialEq)]
 pub enum DiffLine {
@@ -105,25 +106,6 @@ where
         }
         _ => print_diff_basic(diff, get_section_title),
     }
-
-    // isatty shamelessly adapted from cargo.
-    #[cfg(unix)]
-    fn isatty() -> bool {
-        extern crate libc;
-
-        unsafe { libc::isatty(libc::STDOUT_FILENO) != 0 }
-    }
-    #[cfg(windows)]
-    fn isatty() -> bool {
-        extern crate kernel32;
-        extern crate winapi;
-
-        unsafe {
-            let handle = kernel32::GetStdHandle(winapi::winbase::STD_OUTPUT_HANDLE);
-            let mut out = 0;
-            kernel32::GetConsoleMode(handle, &mut out) != 0
-        }
-    }
 }
 
 fn print_diff_fancy<F>(
diff --git a/src/utils.rs b/src/utils.rs
index 9a31289e8eb2..bd46ef1bc6ad 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -516,3 +516,22 @@ pub fn left_most_sub_expr(e: &ast::Expr) -> &ast::Expr {
         _ => e,
     }
 }
+
+// isatty shamelessly adapted from cargo.
+#[cfg(unix)]
+pub fn isatty() -> bool {
+    extern crate libc;
+
+    unsafe { libc::isatty(libc::STDOUT_FILENO) != 0 }
+}
+#[cfg(windows)]
+pub fn isatty() -> bool {
+    extern crate kernel32;
+    extern crate winapi;
+
+    unsafe {
+        let handle = kernel32::GetStdHandle(winapi::winbase::STD_OUTPUT_HANDLE);
+        let mut out = 0;
+        kernel32::GetConsoleMode(handle, &mut out) != 0
+    }
+}