diff --git a/tools/xen/build_xva.sh b/tools/xen/build_xva.sh
index 958102b29c..fbbfd6fbe5 100755
--- a/tools/xen/build_xva.sh
+++ b/tools/xen/build_xva.sh
@@ -21,9 +21,19 @@ set -o xtrace
 # This directory
 TOP_DIR=$(cd $(dirname "$0") && pwd)
 
+# Source lower level functions
+. $TOP_DIR/../../functions
+
 # Include onexit commands
 . $TOP_DIR/scripts/on_exit.sh
 
+# xapi functions
+. $TOP_DIR/functions
+
+# Determine what system we are running on.
+# Might not be XenServer if we're using xenserver-core
+GetDistro
+
 # Source params - override xenrc params in your localrc to suite your taste
 source xenrc
 
diff --git a/tools/xen/prepare_guest_template.sh b/tools/xen/prepare_guest_template.sh
index 546ac99cd9..4fa70d377d 100755
--- a/tools/xen/prepare_guest_template.sh
+++ b/tools/xen/prepare_guest_template.sh
@@ -22,9 +22,19 @@ set -o xtrace
 # This directory
 TOP_DIR=$(cd $(dirname "$0") && pwd)
 
+# Source lower level functions
+. $TOP_DIR/../../functions
+
 # Include onexit commands
 . $TOP_DIR/scripts/on_exit.sh
 
+# xapi functions
+. $TOP_DIR/functions
+
+# Determine what system we are running on.
+# Might not be XenServer if we're using xenserver-core
+GetDistro
+
 # Source params - override xenrc params in your localrc to suite your taste
 source xenrc
 
diff --git a/tools/xen/xenrc b/tools/xen/xenrc
index b355a10d4f..278bb9b909 100644
--- a/tools/xen/xenrc
+++ b/tools/xen/xenrc
@@ -91,4 +91,7 @@ UBUNTU_INST_GATEWAY=""
 # Set the size to 0 to avoid creation of additional disk.
 XEN_XVDB_SIZE_GB=0
 
+restore_nounset=`set +o | grep nounset`
+set +u
 source ../../stackrc
+$restore_nounset