diff --git a/tests/testthat/helper.R b/tests/testthat/helper.R
index 8dec384..b8f6cdc 100644
--- a/tests/testthat/helper.R
+++ b/tests/testthat/helper.R
@@ -40,9 +40,13 @@ skip_if_cannot_knit <- function() {
 
 # Used to skip tests that will fail when locale is set to C, for
 # instance `with_language()` tests. These tests should only be run
-# when using a locale like `en_US`. The check is cautious and simple:
-# If unset we assume the default might be C or maybe `LANG` is set to C.
+# when using a locale like `en_US`.
 skip_if_c_locale <- function() {
   lc_all <- Sys.getenv("LC_ALL", "")
-  skip_if(lc_all %in% c("", "C", "C.UTF-8"))
+  skip_if(lc_all %in% c("C", "C.UTF-8"))
+
+  if (lc_all == "") {
+    lang <- Sys.getenv("LANG", "")
+    skip_if(lang %in% c("C", "C.UTF-8"))
+  }
 }