From b23878ae76139230da0042204f293d148f53f25d Mon Sep 17 00:00:00 2001
From: Jonathan Keane <jkeane@gmail.com>
Date: Thu, 20 Jun 2024 18:47:08 -0500
Subject: [PATCH] Oops, can't use NULL in unset

---
 r/tools/nixlibs.R | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/r/tools/nixlibs.R b/r/tools/nixlibs.R
index 51f8834599a2a..fc79e06328005 100644
--- a/r/tools/nixlibs.R
+++ b/r/tools/nixlibs.R
@@ -827,7 +827,11 @@ set_thirdparty_urls <- function(env_var_list) {
 # env_var_list
 is_feature_requested <- function(env_varname, env_var_list, default = env_is("LIBARROW_MINIMAL", "false")) {
   # look in the environment first, but then use the env_var_list if nothing is found
-  env_value <- tolower(Sys.getenv(env_varname, env_var_list[[env_varname]]))
+  env_var_list_value <- env_var_list[[env_varname]]
+  if (is.null(env_var_list_value)) {
+    env_var_list_value <- ""
+  }
+  env_value <- tolower(Sys.getenv(env_varname, env_var_list_value))
   if (identical(env_value, "off")) {
     # If e.g. ARROW_MIMALLOC=OFF explicitly, override default
     requested <- FALSE