diff --git a/cjdns.spec b/cjdns.spec
index 766df0f..333d7e6 100644
--- a/cjdns.spec
+++ b/cjdns.spec
@@ -330,8 +330,12 @@ fi
 rm -rf node_build/dependencies/libuv
 %else
 rm -rf node_build/dependencies/libuv/build/gyp # use system gyp
+%ifarch s390x
+sed -i -e '/optimizeLevel:/ s/-O0/-O1/' node_build/make.js
+%else
 sed -i -e '/optimizeLevel:/ s/-O0/-O2/' node_build/make.js
 %endif
+%endif
 %patch19 -p1 -b .fuzz
 #patch20 -p1 -b .sysctl
 %patch22 -b .gcc10