diff --git a/include/tz_database.hrl b/include/tz_database.hrl
index 4cfd583..bbde520 100644
--- a/include/tz_database.hrl
+++ b/include/tz_database.hrl
@@ -35,7 +35,7 @@
       %%   Discarded excess rules for Zone Africa/El_Aaiun.
       %%   Moving rule to beginning of day for Zone America/Godthab.
       %%   Moving rule to beginning of day for Zone America/Godthab.
-      %%   Rounded timezone rules of Asia/Tehran to week 3 in march and september
+      %%   Removed DST from Iran and Asia/Tehran
 
       {"Africa/Abidjan",{"GMT","GMT"},undef,0,0,undef,{0,0},undef,{0,0}},
       {"Africa/Accra",{"GMT","GMT"},undef,0,0,undef,{0,0},undef,{0,0}},
@@ -347,7 +347,7 @@
       {"Asia/Taipei",{"CST","CST"},undef,480,0,undef,{0,0},undef,{0,0}},
       {"Asia/Tashkent",{"UZT","UZT"},undef,300,0,undef,{0,0},undef,{0,0}},
       {"Asia/Tbilisi",{"GET","GET"},undef,240,0,undef,{0,0},undef,{0,0}},
-      {"Asia/Tehran",{"IRST","IRST"},{"IRDT","IRDT"},210,60,{3,sat,mar},{0,0},{3,sat,sep},{0,0}},
+      {"Asia/Tehran",{"IRST","IRST"},undef,210,0,undef,{0,0},undef,{0,0}},
       {"Asia/Tel_Aviv",{"IST","IST"},{"IDT","IDT"},120,60,{4,fri,mar},{2,0},{last,sun,oct},{2,0}},
       {"Asia/Thimbu",{"BTT","BTT"},undef,360,0,undef,{0,0},undef,{0,0}},
       {"Asia/Thimphu",{"BTT","BTT"},undef,360,0,undef,{0,0},undef,{0,0}},
@@ -535,7 +535,7 @@
       {"Indian/Mauritius",{"MUT","MUT"},undef,240,0,undef,{0,0},undef,{0,0}},
       {"Indian/Mayotte",{"EAT","EAT"},undef,180,0,undef,{0,0},undef,{0,0}},
       {"Indian/Reunion",{"RET","RET"},undef,240,0,undef,{0,0},undef,{0,0}},
-      {"Iran",{"IRST","IRST"},{"IRDT","IRDT"},210,60,undef,{0,0},undef,{0,0}},
+      {"Iran",{"IRST","IRST"},undef,210,0,undef,{0,0},undef,{0,0}},
       {"Israel",{"IST","IST"},{"IDT","IDT"},120,60,{4,fri,mar},{2,0},{last,sun,oct},{2,0}},
       {"Jamaica",{"EST","EST"},undef,-300,0,undef,{0,0},undef,{0,0}},
       {"Japan",{"JST","JST"},undef,540,0,undef,{0,0},undef,{0,0}},
diff --git a/src/localtime.erl b/src/localtime.erl
index 1cbcf94..0bf952a 100644
--- a/src/localtime.erl
+++ b/src/localtime.erl
@@ -255,10 +255,12 @@ tr_char_test() ->
    ?assertEqual("A_C_E", tr_char("A C E", ?SPACE_CHAR, $_)).
 
 tz_name_test() ->
-    ?assertEqual({"CET", "CET"}, tz_name({{2008,12,10},{15,30,0}}, "Europe/Amsterdam")),
-    ?assertEqual({"IRST", "IRST"}, tz_name({{2008,12,10},{15,30,0}}, "Asia/Tehran")),
-    ?assertEqual({"IRDT", "IRDT"}, tz_name({{2020,5,4},{15,30,0}}, "Asia/Tehran")).
-
+   ?assertEqual({"CET", "CET"}, tz_name({{2008,12,10},{15,30,0}}, "Europe/Amsterdam")),
+   %%% No DST in Iran
+   ?assertEqual({"IRST", "IRST"}, tz_name({{2008,12,10},{15,30,0}}, "Asia/Tehran")),
+   ?assertEqual({"IRST", "IRST"}, tz_name({{2020,5,4},{15,30,0}}, "Asia/Tehran")),
+   ?assertEqual({"IRST", "IRST"}, tz_name({{2008,12,10},{15,30,0}}, "Iran")),
+   ?assertEqual({"IRST", "IRST"}, tz_name({{2020,5,4},{15,30,0}}, "Iran")).
 
 get_timezone_test() ->
    ?assertEqual("America/Los_Angeles", get_timezone("America/Los Angeles")).