diff --git a/test/check_common_fn.in b/test/check_common_fn.in
index 92239f61..f4b4c9ab 100755
--- a/test/check_common_fn.in
+++ b/test/check_common_fn.in
@@ -21,11 +21,13 @@ SKIP_TEST_EXITCODE=77
 # results
 TZ=CUT
 # both 'en_US' and 'en_US.utf8' might be defined on some platforms
-if locale -a 2>/dev/null ; then 
+if locale -a >/dev/null 2>&1 ; then 
   LC_TIME=$(locale -a | grep 'en_US' | grep -v 'utf8' &2>/dev/null)
-else
-  LC_TIME=en_US
 fi
+[[ -z $LC_TIME ]] && {
+  LC_TIME=${LC_TIME:-en_US}
+}>/dev/null 2>&1
+
 export TZ LC_TIME
 
 check_result() {