diff --git a/pkgs/by-name/zt/ztools/package.nix b/pkgs/by-name/zt/ztools/package.nix
index 1baf1fe466c8..ec350f76065c 100644
--- a/pkgs/by-name/zt/ztools/package.nix
+++ b/pkgs/by-name/zt/ztools/package.nix
@@ -10,7 +10,7 @@ stdenv.mkDerivation (finalAttrs: {
   version = "7/3.1";
 
   src = fetchurl {
-    url = "http://mirror.ifarchive.org/if-archive/infocom/tools/ztools/ztools731.tar.gz";
+    url = "https://mirror.ifarchive.org/if-archive/infocom/tools/ztools/ztools731.tar.gz";
     hash = "sha256-vlQX0/fCAr88KJwMnYUSROFOg9tfVK5Hz58AUDuhNXg=";
   };