diff --git a/src/editfns.c b/src/editfns.c
index dbcb316..4c542bd 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -2359,6 +2359,11 @@ set_time_zone_rule (const char *tzstring)
       xputenv (tzval);
     }
 
+  char const *TZ = getenv ("TZ");
+  fprintf (stderr, ("set_time_zone_rule (\"%s\"); "
+		    "tzval = \"%s\"; getenv (\"TZ\") -> %s\n"),
+	   tzstring ? tzstring : "(null)", tzval, TZ ? TZ : "(null)");
+
 #ifdef HAVE_TZSET
   tzset ();
 #endif