diff --git a/SPECS/rust.spec b/SPECS/rust.spec
index dc5133d..ef7b4eb 100644
--- a/SPECS/rust.spec
+++ b/SPECS/rust.spec
@@ -16,7 +16,7 @@
 %global bootstrap_date 2019-09-26
 
 # Only the specified arches will use bootstrap binaries.
-global bootstrap_arches %{rust_arches}
+%global bootstrap_arches %%{rust_arches}
 
 # Using llvm-static may be helpful as an opt-in, e.g. to aid LLVM rebases.
 %bcond_with llvm_static