diff --git a/defaults/initrd.d/00-common.sh b/defaults/initrd.d/00-common.sh
index 8947008..3211985 100755
--- a/defaults/initrd.d/00-common.sh
+++ b/defaults/initrd.d/00-common.sh
@@ -33,12 +33,12 @@ bad_msg() {
 
 quiet_kmsg() {
     # if QUIET is set make the kernel less chatty
-    [ -n "$QUIET" ] && echo '0' > /proc/sys/kernel/printk
+    [ -n "${QUIET}" ] && echo "0" > /proc/sys/kernel/printk
 }
 
 verbose_kmsg() {
     # if QUIET is set make the kernel less chatty
-    [ -n "$QUIET" ] && echo '6' > /proc/sys/kernel/printk
+    [ -n "${QUIET}" ] && echo "6" > /proc/sys/kernel/printk
 }
 
 test_success() {