diff --git a/pkgs/by-name/pe/perseus/package.nix b/pkgs/by-name/pe/perseus/package.nix
index 8e83890ea2f9..27bb58ec764e 100644
--- a/pkgs/by-name/pe/perseus/package.nix
+++ b/pkgs/by-name/pe/perseus/package.nix
@@ -13,7 +13,7 @@ stdenv.mkDerivation {
   hardeningDisable = [ "stackprotector" ];
 
   src = fetchurl {
-    url = "http://people.maths.ox.ac.uk/nanda/source/perseus_4_beta.zip";
+    url = "https://people.maths.ox.ac.uk/nanda/source/perseus_4_beta.zip";
     sha256 = "sha256-cnkJEIC4tu+Ni7z0cKdjmLdS8QLe8iKpdA8uha2MeSU=";
   };