diff --git a/Dockerfile b/Dockerfile
index 1cf70546..8bd81861 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -46,7 +46,7 @@ RUN easy-add --var os=${TARGETOS} --var arch=${TARGETARCH}${TARGETVARIANT} \
   --var version=0.1.1 --var app=maven-metadata-release --file {{.app}} \
   --from https://github.com/itzg/{{.app}}/releases/download/{{.version}}/{{.app}}_{{.version}}_{{.os}}_{{.arch}}.tar.gz
 
-ARG MC_HELPER_VERSION=1.24.20
+ARG MC_HELPER_VERSION=1.24.21
 ARG MC_HELPER_BASE_URL=https://github.com/itzg/mc-image-helper/releases/download/${MC_HELPER_VERSION}
 RUN curl -fsSL ${MC_HELPER_BASE_URL}/mc-image-helper-${MC_HELPER_VERSION}.tgz \
   | tar -C /usr/share -zxf - \
diff --git a/examples/docker-compose-simple.yml b/examples/docker-compose-simple.yml
index caa1c39d..2da9f045 100644
--- a/examples/docker-compose-simple.yml
+++ b/examples/docker-compose-simple.yml
@@ -6,7 +6,7 @@ services:
     tty: true
     stdin_open: true
     ports:
-      - 25565:25565
+      - "25565:25565"
     environment:
       EULA: "TRUE"
     volumes:
diff --git a/scripts/start-setupMounts b/scripts/start-setupMounts
index c9460b66..c11f5f04 100755
--- a/scripts/start-setupMounts
+++ b/scripts/start-setupMounts
@@ -14,11 +14,11 @@
 set -e
 isDebugging && set -x
 
-if isTrue ${SYNC_SKIP_NEWER_IN_DESTINATION}; then
+if isTrue "${SYNC_SKIP_NEWER_IN_DESTINATION}"; then
   updateArg="--skip-newer-in-destination"
 fi
 
-if isTrue ${REPLACE_ENV_DURING_SYNC}; then
+if isTrue "${REPLACE_ENV_DURING_SYNC}"; then
   subcommand=sync-and-interpolate
 else
   subcommand=sync
@@ -34,7 +34,7 @@ if [ -d /plugins ]; then
         --replace-env-file-suffixes="${REPLACE_ENV_SUFFIXES}" \
         --replace-env-excludes="${REPLACE_ENV_VARIABLES_EXCLUDES}" \
         --replace-env-exclude-paths="${REPLACE_ENV_VARIABLES_EXCLUDE_PATHS}" \
-        --replace-env-prefix=${REPLACE_ENV_VARIABLE_PREFIX} \
+        --replace-env-prefix="${REPLACE_ENV_VARIABLE_PREFIX}" \
         /plugins /data/plugins
       ;;
   esac
@@ -50,7 +50,7 @@ if [ -d /mods ]; then
     --replace-env-file-suffixes="${REPLACE_ENV_SUFFIXES}" \
     --replace-env-excludes="${REPLACE_ENV_VARIABLES_EXCLUDES}" \
     --replace-env-exclude-paths="${REPLACE_ENV_VARIABLES_EXCLUDE_PATHS}" \
-    --replace-env-prefix=${REPLACE_ENV_VARIABLE_PREFIX} \
+    --replace-env-prefix="${REPLACE_ENV_VARIABLE_PREFIX}" \
     /mods "${COPY_MODS_DEST}"
 fi
 
@@ -63,7 +63,7 @@ if [ -d /config ]; then
     --replace-env-file-suffixes="${REPLACE_ENV_SUFFIXES}" \
     --replace-env-excludes="${REPLACE_ENV_VARIABLES_EXCLUDES}" \
     --replace-env-exclude-paths="${REPLACE_ENV_VARIABLES_EXCLUDE_PATHS}" \
-    --replace-env-prefix=${REPLACE_ENV_VARIABLE_PREFIX} \
+    --replace-env-prefix="${REPLACE_ENV_VARIABLE_PREFIX}" \
     /config "${COPY_CONFIG_DEST}"
 fi