diff --git a/builder-build b/builder-build
index 4f0020e..da1f33c 100755
--- a/builder-build
+++ b/builder-build
@@ -28,14 +28,22 @@ trigger-builder-nixpacks-builder-build() {
 
   plugn trigger pre-build-nixpacks "$APP" "$SOURCECODE_WORK_DIR"
 
-  local flag_map=$(fn-plugin-property-get-all "builder-nixpacks" "$APP")
-  let NIXPACKS_ARGS=""
-  for flag in ${flag_map[@]} ; do
-    NIXPACKS_ARGS+="$(echo "${flag}" | tr ' ' '=') "
+  local NIXPACKS_ARGS=""
+  local NIXPACKS_FLAGS=$(fn-plugin-property-get-all "builder-nixpacks" "$APP")
+  for flag in $NIXPACKS_FLAGS ; do
+    local value="$(fn-plugin-property-get "builder-nixpacks" "$APP" "$flag")"
+    if [[ -n "$value" ]] ; then
+      NIXPACKS_ARGS="${NIXPACKS_ARGS}${flag}='${value}' "
+    fi
   done
 
-  echo /usr/bin/env "${NIXPACKS_ARGS}" nixpacks build . --name "$IMAGE"
-  /usr/bin/env "${NIXPACKS_ARGS}" nixpacks build . --name "$IMAGE"
+  if [[ -n "$NIXPACKS_ARGS" ]] ; then
+    dokku_info_log2_quiet "nixpacks build . --name $IMAGE --env $NIXPACKS_ARGS"
+    nixpacks build . --name "$IMAGE" --env "$NIXPACKS_ARGS"
+  else
+    dokku_info_log2_quiet "nixpacks build . --name $IMAGE"
+    nixpacks build . --name "$IMAGE"
+  fi
   docker-image-labeler --label=dokku --label=org.label-schema.schema-version=1.0 --label=org.label-schema.vendor=dokku --label=com.dokku.image-stage=build --label=com.dokku.builder-type=pack --label=com.dokku.app-name=$APP "$IMAGE"
 
   plugn trigger post-build-nixpacks "$APP" "$SOURCECODE_WORK_DIR"
diff --git a/internal-functions b/internal-functions
index 4f2a83d..13759b4 100755
--- a/internal-functions
+++ b/internal-functions
@@ -34,7 +34,7 @@ cmd-builder-nixpacks-report-single() {
 
   dokku_log_info2_quiet "${APP} builder-nixpacks information"
   local NIXPACK_KEYS="$(fn-builder-nixpacks-valid-keys)"
-  for key in "${NIXPACK_KEYS[@]}" ; do
+  for key in $NIXPACK_KEYS ; do
     local result="$(fn-plugin-property-get "builder-nixpacks" "$APP" "$key")"
     dokku_log_verbose "$(printf "%-30s %-40s" "${key}" "${result}")"
   done
@@ -42,4 +42,4 @@ cmd-builder-nixpacks-report-single() {
 
 fn-builder-nixpacks-valid-keys() {
   echo "NIXPACKS_APT_PKGS NIXPACKS_BUILD_CACHE_DIRS NIXPACKS_BUILD_CMD NIXPACKS_INSTALL_CACHE_DIRS NIXPACKS_INSTALL_CMD NIXPACKS_LIBS NIXPACKS_NO_CACHE NIXPACKS_NO_MUSL NIXPACKS_PKGS NIXPACKS_START_CMD"
-)
+}
diff --git a/subcommands/set b/subcommands/set
index 78c2ee1..6cd2901 100755
--- a/subcommands/set
+++ b/subcommands/set
@@ -11,24 +11,12 @@ cmd-builder-nixpacks-set() {
   [[ "$1" == "$cmd" ]] && shift 1
   declare APP="$1" KEY="$2" VALUE="$3"
   local VALID_KEYS=$(fn-builder-nixpacks-valid-keys)
-  local VALID_KEYS=(\
-    "NIXPACKS_APT_PKGS" \
-    "NIXPACKS_BUILD_CACHE_DIRS" \
-    "NIXPACKS_BUILD_CMD" \
-    "NIXPACKS_INSTALL_CACHE_DIRS" \
-    "NIXPACKS_INSTALL_CMD" \
-    "NIXPACKS_LIBS" \
-    "NIXPACKS_NO_CACHE" \
-    "NIXPACKS_NO_MUSL" \
-    "NIXPACKS_PKGS" \
-    "NIXPACKS_START_CMD" \
-  )
   verify_app_name "$APP"
 
   [[ -z "$KEY" ]] && dokku_log_fail "No key specified"
 
-  if ! fn-in-array "$KEY" "${VALID_KEYS[@]}"; then
-    dokku_log_fail "Invalid key specified, valid keys include: ${VALID_KEYS[@]}"
+  if ! is_val_in_list "$KEY" "$VALID_KEYS" " "; then
+    dokku_log_fail "Invalid key specified, valid keys include: $VALID_KEYS"
   fi
 
   if [[ -n "$VALUE" ]]; then