diff --git a/debian/changelog b/debian/changelog
index 9eacb71c0..16d72e629 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -4,6 +4,7 @@ linux (3.9-1~experimental.1) UNRELEASED; urgency=low
 
   [ Ben Hutchings ]
   * [rt] Disable until it is updated for Linux 3.9 or later
+  * Build-Depend on bc, needed to build kernel/timeconst.h
 
  -- Ben Hutchings <ben@decadent.org.uk>  Mon, 06 May 2013 13:17:52 +0100
 
diff --git a/debian/templates/control.source.in b/debian/templates/control.source.in
index f4d34c6d5..1bf01c4a8 100644
--- a/debian/templates/control.source.in
+++ b/debian/templates/control.source.in
@@ -3,7 +3,7 @@ Priority: optional
 Maintainer: Debian Kernel Team <debian-kernel@lists.debian.org>
 Uploaders: Bastian Blank <waldi@debian.org>, Frederik Schüler <fs@debian.org>, maximilian attems <maks@debian.org>, Ben Hutchings <ben@decadent.org.uk>
 Standards-Version: 3.9.2
-Build-Depends: debhelper (>> 7), cpio, kmod | module-init-tools, python (>= 2.7), lzma [armel], kernel-wedge (>= 2.84), quilt, patchutils
+Build-Depends: debhelper (>> 7), cpio, kmod | module-init-tools, python (>= 2.7), lzma [armel], kernel-wedge (>= 2.84), quilt, patchutils, bc
 Build-Depends-Indep: bzip2, xmlto
 Vcs-Svn: svn://svn.debian.org/svn/kernel/dists/trunk/linux/
 Vcs-Browser: http://anonscm.debian.org/viewvc/kernel/dists/trunk/linux/