diff --git a/Dockerfile b/Dockerfile
index 8f75fa1..4c8ccd4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,8 +5,8 @@ ARG HELM_VERSION
 RUN apk add bash curl git openssl && \
     curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 --output /tmp/install.sh
 
-RUN [[ ${HELM_VERSION} == "" ]]; bash /tmp/install.sh
-RUN [[ ${HELM_VERSION} != "" ]]; bash /tmp/install.sh --version ${HELM_VERSION}
+RUN if [[ -z "${HELM_VERSION+x}" ]]; then bash /tmp/install.sh; fi
+RUN if [[ -n "${HELM_VERSION+x}" ]]; then bash /tmp/install.sh --version "${HELM_VERSION}"; fi
 
 RUN rm /tmp/install.sh