diff --git a/src/librustc_back/target/mod.rs b/src/librustc_back/target/mod.rs
index 22d966014da1c..402fbcd8d8d8e 100644
--- a/src/librustc_back/target/mod.rs
+++ b/src/librustc_back/target/mod.rs
@@ -272,6 +272,7 @@ impl Target {
         }
 
         key!(cpu);
+        key!(ar);
         key!(linker);
         key!(relocation_model);
         key!(code_model);