1 files changed, 11 insertions, 3 deletions

diff --git a/hash.c b/hash.c
index 6b3f844095..0b3745cf6e 100644
--- a/hash.c
+++ b/hash.c
@@ -4711,6 +4711,17 @@ env_delete(VALUE name)
 
     nam = env_name(name);
     val = getenv(nam);
+
+    /*
+     * ENV['TZ'] = nil has a special meaning.
+     * TZ is no longer considered up-to-date and ruby call tzset() as needed.
+     * It could be useful if sysadmin change /etc/localtime.
+     * This hack might works only on Linux glibc.
+     */
+    if (ENVMATCH(nam, TZ_ENV)) {
+        ruby_tz_uptodate_p = FALSE;
+    }
+
     if (val) {
 	VALUE value = env_str_new2(val);
 
@@ -4718,9 +4729,6 @@ env_delete(VALUE name)
 	if (ENVMATCH(nam, PATH_ENV)) {
 	    RB_GC_GUARD(name);
 	}
-	else if (ENVMATCH(nam, TZ_ENV)) {
-	    ruby_tz_uptodate_p = false;
-	}
 	return value;
     }
     return Qnil;