diff --git a/nbdkit.spec b/nbdkit.spec
index bd3cf3d..04b98e9 100644
--- a/nbdkit.spec
+++ b/nbdkit.spec
@@ -1,8 +1,11 @@
 %global _hardened_build 1
 
 %ifarch %{kernel_arches}
+# ... except that it doesn't work on s390, so:
+%ifnarch s390 s390x
 %global have_libguestfs 1
 %endif
+%endif
 
 # We can only compiler the OCaml plugin on platforms which have native
 # OCaml support (not bytecode).