diff --git a/firefox.spec b/firefox.spec
index 11e5d3a..e2ac7f1 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -7,6 +7,10 @@
 %global create_debuginfo  1
 %global system_nss        1
 
+# There are still build problems on s390x, see
+# https://koji.fedoraproject.org/koji/taskinfo?taskID=55048351
+ExcludeArch: s390x
+
 %ifarch armv7hl
 %global create_debuginfo  0
 %endif