diff --git a/pkgs/by-name/di/dieharder/package.nix b/pkgs/by-name/di/dieharder/package.nix
index e99f3c4286a8..e12640551fb8 100644
--- a/pkgs/by-name/di/dieharder/package.nix
+++ b/pkgs/by-name/di/dieharder/package.nix
@@ -11,7 +11,7 @@ stdenv.mkDerivation (finalAttrs: {
   version = "3.31.1";
 
   src = fetchurl {
-    url = "http://webhome.phy.duke.edu/~rgb/General/dieharder/dieharder-${finalAttrs.version}.tgz";
+    url = "https://webhome.phy.duke.edu/~rgb/General/dieharder/dieharder-${finalAttrs.version}.tgz";
     hash = "sha256-bP8P+DlMVTVJrHQzNZzPyVX7JnlCYDFGIN+l5M1Lcn8=";
   };