diff --git a/scripts/check-version.sh b/scripts/check-version.sh
index 6adcf77..0f588c0 100755
--- a/scripts/check-version.sh
+++ b/scripts/check-version.sh
@@ -3,7 +3,7 @@ set -e
 
 RAW_VERSION=""
 
-if [ -n "${VERSION_FILE}" ] && [ -f "${VERSION_FILE}" ]; then
+if [ -n "${VERSION_FILE-}" ] && [ -f "${VERSION_FILE-}" ]; then
   RAW_VERSION=$(sed -n 's/^version:[[:space:]]*\([^[:space:]]*\).*/\1/p' "${VERSION_FILE}")
   if [ -z "${RAW_VERSION}" ]; then
     if echo "${VERSION_FILE}" | grep -q -E '\.json$'; then
@@ -35,7 +35,7 @@ echo "gitea-ci-library - Tunnistettu Major.Minor versio: $BASE_VERSION"
 TAGS_JSON=$(curl -s -f -H "Authorization: token ${GITEA_TOKEN}" \
   "${SERVER_URL}/api/v1/repos/${REPO}/tags")
 
-TAG=$(echo "$TAGS_JSON" | jq -r --arg prefix "${GIT_TAG_PREFIX}" --arg sha "${SHA}" '
+TAG=$(echo "$TAGS_JSON" | jq -r --arg prefix "${GIT_TAG_PREFIX-}" --arg sha "${SHA}" '
   if type == "array" then
     .[] | select(.commit.sha == $sha and (.name | startswith($prefix))) | .name
   else empty end' | head -1)
@@ -49,7 +49,7 @@ if [ -n "$TAG" ]; then
 else
   echo "ARTIFACT_EXISTS=false" > /tmp/build-ctx/build.env
 
-  HIGHEST_PATCH=$(echo "$TAGS_JSON" | jq -r --arg prefix "${GIT_TAG_PREFIX}" --arg bv "${GIT_TAG_PREFIX}${BASE_VERSION}." '
+  HIGHEST_PATCH=$(echo "$TAGS_JSON" | jq -r --arg prefix "${GIT_TAG_PREFIX-}" --arg bv "${GIT_TAG_PREFIX-}${BASE_VERSION}." '
     if type == "array" then .[] | .name | select(startswith($bv)) | sub($bv; "") | tonumber else empty end' | sort -rn | head -1)
 
   if [ -z "$HIGHEST_PATCH" ]; then NEXT_PATCH=0; else NEXT_PATCH=$((HIGHEST_PATCH + 1)); fi