diff --git a/debian/util.sh b/debian/util.sh
index a30e5bf260..ad5253f2c7 100755
--- a/debian/util.sh
+++ b/debian/util.sh
@@ -274,26 +274,30 @@ get_sources () {
   while read type path distro components; do
     test "$type" = deb || continue
     printf "$type $path $tgt_distro $components\n"
-  done < /etc/apt/sources.list
+  done < "$2"
 }
 
 get_mirrors () {
-  get_sources "$1" | tr '\n' '|' | head -c-1; echo
+  file=${2-/etc/apt/sources.list}
+  announce "Using apt sources file: $file"
+  get_sources "$1" "$file" | tr '\n' '|' | head -c-1; echo
 }
 
 build_debs () {
   {
     set -e
     local OPTIND OPTARG debug_hook=false hookdir="" cow_build_opts=""
-    local keep_pbuilder_config=false
+    local keep_pbuilder_config=false keyring="" custom_keyring=""
     local use_system_sources=false
-    while getopts 'Bbdkt' o "$@"; do
+    while getopts 'BbdK:kT:t' o "$@"; do
       case "$o" in
         B) cow_build_opts="--debbuildopts '-B'";;
         b) cow_build_opts="--debbuildopts '-b'";;
         d) debug_hook=true;;
         k) keep_pbuilder_config=true;;
-        t) use_system_sources=true;;
+        K) custom_keyring="$OPTARG";;
+        t) use_system_sources=true; custom_sources_file="/etc/apt/sources.list";;
+        T) use_custom_sources=true; custom_sources_file="$OPTARG";;
       esac
     done
     shift $(($OPTIND-1))
@@ -309,6 +313,12 @@ build_debs () {
     [ -x "$(which cowbuilder)" ] \
       || err "package cowbuilder isn't installed"
     local cow_img=/var/cache/pbuilder/base-$distro-$arch.cow
+    if [ -e "$custom_keyring" ]; then
+      keyring="$custom_keyring"
+    else
+      keyring="$(mktemp /tmp/keyringXXXXXXXX.asc)"
+      apt-key exportall > "$keyring"
+    fi
     cow () {
       if ! $use_system_sources; then
         cowbuilder "$@" \
@@ -316,17 +326,18 @@ build_debs () {
           --architecture $arch \
           --basepath $cow_img
       else
-        local keyring="$(mktemp /tmp/keyringXXXXXXXX.asc)"
-        apt-key exportall > "$keyring"
         cowbuilder "$@" \
           --distribution $distro \
           --architecture $arch \
           --basepath $cow_img \
           --keyring "$keyring" \
-          --othermirror "$(get_mirrors $distro)"
-        rm -f $keyring
+          --othermirror "$(get_mirrors $distro $custom_sources_file)"
       fi
     }
+    if [ ! -e "$custom_keyring" ]; then
+      # Cleanup script created temporary file
+      rm -f $keyring
+    fi
     if ! [ -d $cow_img ]; then
       announce "Creating base $distro-$arch image..."
       local x=30
@@ -466,6 +477,9 @@ commands:
     -i Auto install build deps on host system
     -j Build debs in parallel
     -k Don't override pbuilder image configurations
+    -K [/path/to/keyring.asc]
+       Use custom keyring file for sources.list in build environment 
+       in the format of: apt-key exportall > /path/to/file.asc
     -l <modules>
     -m [ quicktest | non-dfsg ]
       Choose custom list of modules to build
@@ -477,6 +491,8 @@ commands:
     -s [ paranoid | reckless ]
       Set FS bootstrap/build -j flags
     -t Use system /etc/apt/sources.list in build environment
+    -T [/path/to/sources.list]
+       Use custom /etc/apt/sources.list in build environment
     -u <suite-postfix>
       Specify a custom suite postfix
     -v Set version
@@ -490,7 +506,12 @@ commands:
     -b Binary-only build
     -d Enable cowbuilder debug hook
     -k Don't override pbuilder image configurations
+    -K [/path/to/keyring.asc]
+       Use custom keyring file for sources.list in build environment 
+       in the format of: apt-key exportall > /path/to/file.asc
     -t Use system /etc/apt/sources.list in build environment
+    -T [/path/to/sources.list]
+       Use custom /etc/apt/sources.list in build environment
 
   create-dbg-pkgs