diff --git a/src/bin/miri.rs b/src/bin/miri.rs
index 0f28a0c5d8dc..6e67246d2ca1 100644
--- a/src/bin/miri.rs
+++ b/src/bin/miri.rs
@@ -184,10 +184,10 @@ fn main() {
     // FIXME: Ideally we'd turn a bad build env into a compile-time error, but
     // CTFE does not seem powerful enough for that yet.
     if let Some(sysroot) = compile_time_sysroot() {
-        let sysroot_flag = "--sysroot".to_string();
-        if !rustc_args.contains(&sysroot_flag) {
+        let sysroot_flag = "--sysroot";
+        if !rustc_args.iter().any(|e| e == sysroot_flag) {
             // We need to overwrite the default that librustc would compute.
-            rustc_args.push(sysroot_flag);
+            rustc_args.push(sysroot_flag.to_owned());
             rustc_args.push(sysroot);
         }
     }