diff --git a/cd.sh b/cd.sh
index 88d7d0c..80e9ee7 100644
--- a/cd.sh
+++ b/cd.sh
@@ -42,7 +42,8 @@ cd_main () {
 cd_set_environment_variables () {
     cd_step "Set environment variables"
     # operating system
-    case "$(cd_grep_os ID)" in
+    CD_OS_ID="$(cd_grep_os ID)"
+    case "${CD_OS_ID}" in
         "almalinux")
             CD_OS_ID="${CD_OS_ALMA}"
             CD_OS_VERSION=$(cd_grep_os VERSION_ID \
@@ -57,11 +58,15 @@ cd_set_environment_variables () {
             CD_OS_ID="${CD_OS_DEBIAN}"
             CD_OS_VERSION="$(cd_grep_os VERSION_CODENAME)"
         ;;
+        *) cd_error_os "CD_OS_ID" ;;
     esac
     # universal
     CD_DNS_FILE="/etc/resolv.conf"
     CD_PKG_CA="ca-certificates"
     CD_PKG_GIT="git"
+    # common
+    case "${CD_OS_ID}" in
+    esac
     #
     case "${CD_OS_ID}" in
         "${CD_OS_ALMA}")
@@ -145,7 +150,6 @@ Dir::Etc::SourceParts \"\";
             CD_PYTHON_PACKAGE="python3"
             CD_PYTHON_PACKAGES="/usr/lib/python3/dist-packages"
         ;;
-        *) cd_error_os "CD_OS_ID" ;;
     esac
     # variables
     [ "${CD_CA_1}" ] && CD_CA=true