diff --git a/xCAT-genesis-builder/xCAT-genesis-base.spec b/xCAT-genesis-builder/xCAT-genesis-base.spec
index 1a6f0f212..f2b790e51 100644
--- a/xCAT-genesis-builder/xCAT-genesis-base.spec
+++ b/xCAT-genesis-builder/xCAT-genesis-base.spec
@@ -12,6 +12,14 @@ Release: %{?release:%{release}}%{!?release:%(cat Release)}
 %ifarch aarch64
 %define tarch aarch64
 %endif
+%ifarch riscv64
+%define tarch riscv64
+%endif
+# An arch missing from the ladder above leaves %{tarch} unexpanded, and rpm then builds a package
+# with a macro in its NAME instead of failing. Stop the build here instead.
+%if ! %{defined tarch}
+%{error:no genesis tarch for %{_target_cpu} -- add an %%ifarch branch above}
+%endif
 BuildArch: noarch
 %define name	xCAT-genesis-base-%{tarch}
 %define __spec_install_post :
diff --git a/xCAT-genesis-scripts/xCAT-genesis-scripts.spec b/xCAT-genesis-scripts/xCAT-genesis-scripts.spec
index f42ffd477..1760f86d7 100644
--- a/xCAT-genesis-scripts/xCAT-genesis-scripts.spec
+++ b/xCAT-genesis-scripts/xCAT-genesis-scripts.spec
@@ -10,6 +10,14 @@
 %ifarch aarch64
 %define tarch aarch64
 %endif
+%ifarch riscv64
+%define tarch riscv64
+%endif
+# An arch missing from the ladder above leaves %{tarch} unexpanded, and rpm then builds a package
+# with a macro in its NAME instead of failing. Stop the build here instead.
+%if ! %{defined tarch}
+%{error:no genesis tarch for %{_target_cpu} -- add an %%ifarch branch above}
+%endif
 %define rpminstallroot /opt/xcat/share/xcat/netboot/genesis/%{tarch}/fs
 BuildArch: noarch
 %define name	xCAT-genesis-scripts-%{tarch}