Shell Programming and Scripting

I use the following as part of a script to correct for a faulty hostname file.

Code:

# get the domain name
read -r thehostname < /etc/hostname
dom="$(echo $thehostname | cut -d'.' -f2)"
numchar=${#dom}
if [ "$numchar" -le 5 ]
then
echo "It appears as though the hostname is not correctly set."
echo "Hostname has $thehostname as your hostname." 
echo "Please enter the domain name"
read realdom
dom=$realdom
thehostname="svr.$realdom.com"
sed -i 1c"$thehostname" /etc/hostname
fi

The code works fine, but it always adds a blank line at the end of the hostname file. (the extra is noticed by an additional byte as well as in notepad++.)

It does not appear to be a real problem, since it doesnt actually affect anything else. But I would like the script to be more precise and not add anything.

Am I using sed incorrectly? Is there a switch that would prevent it from adding the newline?