diff --git a/rust.spec b/rust.spec
index c03d057..9cd5d1b 100644
--- a/rust.spec
+++ b/rust.spec
@@ -62,24 +62,23 @@ Conflicts:      rustc-bootstrap
 Provides:       rustc = %{version}
 Provides:       rustc-stable = %{version}
 BuildRoot:      %{_tmppath}/%{name}-%{version}-build
+# Restrict the architectures as building rust relies on being initially
+# bootstrapped before we can build the n+1 release
 ExclusiveArch:  %{ix86} x86_64 %{arm} aarch64 ppc64 ppc64le s390x
 
 %if 0%{?suse_version}
 BuildRequires:  fdupes
 %endif
 
-%ifarch %{arm} aarch64 ppc64 ppc64le s390x
-BuildRequires:  cargo-bootstrap
-BuildRequires:  rustc-bootstrap >= %{prev_version}
-%else
-%if %{with bootstrap} || (0%{?suse_version} < 1330 && 0%{?sle_version} < 120300)
+# There are no successful builds for less than TW or Leap 42.2, so bootstrap
+# until such time that there is.
+%if %{with bootstrap} || (0%{?suse_version} < 1330 && 0%{?sle_version} < 120200)
 BuildRequires:  cargo-bootstrap
 BuildRequires:  rustc-bootstrap >= %{prev_version}
 %else
 BuildRequires:  cargo
 BuildRequires:  rust >= %{prev_version}
 %endif
-%endif
 
 %description
 Rust is a systems programming language focused on three goals: