diff --git a/trunk/PKGBUILD b/trunk/PKGBUILD
index cd60e45..fd5280c 100644
--- a/trunk/PKGBUILD
+++ b/trunk/PKGBUILD
@@ -35,7 +35,7 @@ makedepends=(
   yelp-tools
 )
 source=(
-  git+https://github.com/CanonicalLtd/lightdm.git#tag=${pkgver}
+  git+https://github.com/CanonicalLtd/lightdm.git#tag=${pkgver}?signed
   lightdm.service
   lightdm.sysusers
   lightdm.tmpfiles
@@ -54,6 +54,7 @@ sha256sums=('SKIP'
             'a89566307e1c81c24f037d854cbd472d2f94f8a4b759877a01563a332319f7d6'
             '782a52dc39a7d6f2c6ee31e66897e3502fc14864e3e4ede8e3d1a0da74b8dfdf'
             'd30321a1b490500483b8ed7825fcff2c24a7c760ac627789ff517693888ec3c5')
+validpgpkeys=('497851B5D455C606543F2B9318EAA1890F7C882E') # Robert Ancell
 
 prepare() {
   cd lightdm