diff --git a/elilo/elilo-xcat.spec b/elilo/elilo-xcat.spec
index b8a9156..f9e6070 100644
--- a/elilo/elilo-xcat.spec
+++ b/elilo/elilo-xcat.spec
@@ -23,7 +23,13 @@ Source4: elilo-xcat-3.14-6.noarch.rpm
 # gnu-efi toolchain layout does not support elilo's build: ppc64le (no x86 EFI toolchain) and
 # EL8 (gnu-efi-devel places elf_x86_64_efi.lds under a path elilo's Makefile does not find).
 # elilo-x64.efi is a noarch artifact, so the prebuilt is byte-identical to the compiled one.
-%if "%{_host_cpu}" == "ppc64le" || 0%{?rhel} == 8
+# Separate %ifarch / %if (NOT a single `... || ...` expression): the older rpm inside the EL8/EL9
+# mock chroot does not evaluate an `||` between a string compare and an arithmetic test the way
+# EL10's rpm does, which silently left use_prebuilt unset and pulled in the gnu-efi BuildRequires.
+%ifarch ppc64le
+%global use_prebuilt 1
+%endif
+%if 0%{?rhel} == 8
 %global use_prebuilt 1
 %endif
 BuildRequires: gcc