diff --git a/src/bin/rustfmt.rs b/src/bin/rustfmt.rs
index 2dc0168aa7f..86a4faa05f5 100644
--- a/src/bin/rustfmt.rs
+++ b/src/bin/rustfmt.rs
@@ -82,7 +82,7 @@ fn main() {
 }
 
 fn print_usage<S: Into<String>>(reason: S) {
-    println!("{}\n\r usage: rustfmt [-h Help] [--write-mode=[true/false]] <file_name>", reason.into());
+    println!("{}\n\r usage: rustfmt [-h Help] [--write-mode=[replace|overwrite|display]] <file_name>", reason.into());
 }
 
 fn determine_params<I>(args: I) -> Option<(Vec<String>, WriteMode)>