diff --git a/elements/debootstrap/install.d/10-debian-networking b/elements/debootstrap/install.d/10-debian-networking
index 7e85cbe57..d5cdc1400 100755
--- a/elements/debootstrap/install.d/10-debian-networking
+++ b/elements/debootstrap/install.d/10-debian-networking
@@ -26,7 +26,10 @@ echo $DISTRO_NAME > /etc/hostname
 
 # cloud images expect eth0 and eth1 to use dhcp.
 mkdir -p /etc/network/interfaces.d
-echo "source /etc/network/interfaces.d/*" >> /etc/network/interfaces
+if ! grep -E -q '^source(|-directory) /etc/network/interfaces.d/\*' /etc/network/interfaces; then
+    echo "source /etc/network/interfaces.d/*" >> /etc/network/interfaces
+    echo 'Network configuration set to source /etc/network/interfaces.d/*'
+fi
 for interface in eth0 eth1; do
     cat << EOF | tee /etc/network/interfaces.d/$interface
 auto $interface