diff --git a/ci/ci-debian.Dockerfile b/ci/ci-debian.Dockerfile
index d9880d83e..e827dc0ab 100644
--- a/ci/ci-debian.Dockerfile
+++ b/ci/ci-debian.Dockerfile
@@ -7,8 +7,8 @@ ARG DEBIAN_CODENAME
 ENV CI_RUNNING=true TERM=xterm
 
 # create pi configs to test installation
-RUN touch /boot/cmdline.txt
 RUN touch /boot/config.txt
+RUN echo "logo.nologo" > /boot/cmdline.txt
 
 RUN export DEBIAN_FRONTEND=noninteractive \
   && echo "--- install packages (1) ---" \
diff --git a/installation/routines/optimize_boot_time.sh b/installation/routines/optimize_boot_time.sh
index 13c78287a..0072e5a21 100644
--- a/installation/routines/optimize_boot_time.sh
+++ b/installation/routines/optimize_boot_time.sh
@@ -104,13 +104,13 @@ _optimize_handle_boot_logs() {
     echo "  Disable boot logs"
 
     if [ ! -s "${RPI_BOOT_CMDLINE_FILE}" ];then
-        sudo tee $RPI_BOOT_CMDLINE_FILE <<-EOF
+        sudo tee "${RPI_BOOT_CMDLINE_FILE}" <<-EOF
 ${OPTIMIZE_BOOT_CMDLINE_OPTIONS}
 EOF
     else
         for option in $OPTIMIZE_BOOT_CMDLINE_OPTIONS
         do
-            if ! $(grep -iw "$option" "${RPI_BOOT_CMDLINE_FILE}") ; then
+            if ! grep -qiw "$option" "${RPI_BOOT_CMDLINE_FILE}" ; then
                 sudo sed -i "s/$/ $option/" "${RPI_BOOT_CMDLINE_FILE}"
             fi
         done