diff --git a/cd.sh b/cd.sh
index eddae10..1884737 100644
--- a/cd.sh
+++ b/cd.sh
@@ -350,16 +350,40 @@ Acquire::https::Verify-Peer False;
     # continuous integration platform
     if [ -n "${GITHUB_ACTIONS}" ] ; then
         # github → gitea → forgejo
-        CD_SERVER_URL="${GITHUB_SERVER_URL}"
-        CD_PROJECTS_GROUP="$(dirname "${GITHUB_REPOSITORY}")"
-        CD_PROJECT_NAME="$(basename "${GITHUB_REPOSITORY}")"
-        CD_PROJECT_BRANCH="${GITHUB_REF_NAME}"
+        if [ -n "${GITHUB_SERVER_URL}" ] ; then
+            CD_SERVER_URL="${GITHUB_SERVER_URL}"
+        else
+            cd_error_ci "GITHUB_SERVER_URL"
+        fi
+        if [ -n "${GITHUB_REPOSITORY}" ] ; then
+            CD_PROJECTS_GROUP="$(dirname "${GITHUB_REPOSITORY}")"
+            CD_PROJECT_NAME="$(basename "${GITHUB_REPOSITORY}")"
+        else
+            cd_error_ci "GITHUB_REPOSITORY"
+        fi
+        if [ -n "${GITHUB_REF_NAME}" ] ; then
+            CD_PROJECT_BRANCH="${GITHUB_REF_NAME}"
+        else
+            cd_error_ci "GITHUB_REF_NAME"
+        fi
     elif [ -n "${GITLAB_CI}" ] ; then
         # gitlab
-        CD_SERVER_URL="${CI_SERVER_URL}"
-        CD_PROJECTS_GROUP="$(dirname "${CI_PROJECT_PATH}")"
-        CD_PROJECT_NAME="$(basename "${CI_PROJECT_PATH}")"
-        CD_PROJECT_BRANCH="${CI_COMMIT_BRANCH}"
+        if [ -n "${CI_SERVER_URL}" ] ; then
+            CD_SERVER_URL="${CI_SERVER_URL}"
+        else
+            cd_error_ci "CI_SERVER_URL"
+        fi
+        if [ -n "${CI_PROJECT_PATH}" ] ; then
+            CD_PROJECTS_GROUP="$(dirname "${CI_PROJECT_PATH}")"
+            CD_PROJECT_NAME="$(basename "${CI_PROJECT_PATH}")"
+        else
+            cd_error_ci "CI_PROJECT_PATH"
+        fi
+        if [ -n "${CI_COMMIT_BRANCH}" ] ; then
+            CD_PROJECT_BRANCH="${CI_COMMIT_BRANCH}"
+        else
+            cd_error_ci "CI_COMMIT_BRANCH"
+        fi
     else
         # unsupported
         cd_error_ci "ø"