diff --git a/debian/changelog b/debian/changelog
index 1eb32efa3..b6af1cdc6 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -12,6 +12,7 @@ linux (4.10.7-1~exp1) UNRELEASED; urgency=medium
   [ Ben Hutchings ]
   * netfilter: Enable NF_SOCKET_IPV4, NF_SOCKET_IPV6 as modules
     (Closes: #858897)
+  * [s390x] Set NR_CPUS=256 (Closes: #858731)
 
  -- Ben Hutchings <ben@decadent.org.uk>  Thu, 30 Mar 2017 13:56:41 +0100
 
diff --git a/debian/config/s390x/config b/debian/config/s390x/config
index efcda6676..dedfdab83 100644
--- a/debian/config/s390x/config
+++ b/debian/config/s390x/config
@@ -9,7 +9,7 @@ CONFIG_MARCH_Z900=y
 ## end choice
 CONFIG_COMPAT=y
 CONFIG_SMP=y
-CONFIG_NR_CPUS=32
+CONFIG_NR_CPUS=256
 CONFIG_HOTPLUG_CPU=y
 CONFIG_SCHED_TOPOLOGY=y
 CONFIG_PACK_STACK=y