diff --git a/rpm.spec b/rpm.spec
index 56de2f0..ef42aa4 100644
--- a/rpm.spec
+++ b/rpm.spec
@@ -242,9 +242,16 @@ export LDFLAGS="-Wl,-Bsymbolic-functions -ffunction-sections"
 export CFLAGS="-g -O0 -fno-strict-aliasing -ffunction-sections"
 %endif
 
+cpu="%{_target_cpu}"
+# convert to gnu style cpu version, see config.sub
+%ifarch ppc ppc64 ppc64le
+cpu="${cpu/#ppc/powerpc}"
+%endif
+
 mkdir _build
 cd _build
 cmake .. \
+  -DRPM_HOST_SYSTEM_CPU="$cpu" \
 %ifarch %arm
   -DRPM_HOST_SYSTEM_ABI=gnueabi \
 %endif