diff --git a/gitk b/gitk
index dd80ab8f3b..7a087f123d 100755
--- a/gitk
+++ b/gitk
@@ -11956,7 +11956,7 @@ proc formatdate {d} {
 }
 
 # This list of encoding names and aliases is distilled from
-# http://www.iana.org/assignments/character-sets.
+# https://www.iana.org/assignments/character-sets.
 # Not all of them are supported by Tcl.
 set encoding_aliases {
     { ANSI_X3.4-1968 iso-ir-6 ANSI_X3.4-1986 ISO_646.irv:1991 ASCII