diff --git a/pkgs/by-name/ca/calculix-ccx/package.nix b/pkgs/by-name/ca/calculix-ccx/package.nix
index 72100a5c4b70..408b1e1ddc35 100644
--- a/pkgs/by-name/ca/calculix-ccx/package.nix
+++ b/pkgs/by-name/ca/calculix-ccx/package.nix
@@ -16,7 +16,7 @@ stdenv.mkDerivation (finalAttrs: {
   version = "2.22";
 
   src = fetchurl {
-    url = "http://www.dhondt.de/ccx_${finalAttrs.version}.src.tar.bz2";
+    url = "https://www.dhondt.de/ccx_${finalAttrs.version}.src.tar.bz2";
     hash = "sha256-OpTcx3WjH1cCKXNLNB1rBjAevcdZhj35Aci5vxhUwLw=";
   };