diff --git a/pkgs/development/libraries/mpir/default.nix b/pkgs/development/libraries/mpir/default.nix
index 7f7df407e4e..5e68ad80fc2 100644
--- a/pkgs/development/libraries/mpir/default.nix
+++ b/pkgs/development/libraries/mpir/default.nix
@@ -7,11 +7,11 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ m4 which yasm ];
 
   src = fetchurl {
-    url = "http://mpir.org/mpir-${version}.tar.bz2";
+    url = "https://mpir.org/mpir-${version}.tar.bz2";
     sha256 = "1fvmhrqdjs925hzr2i8bszm50h00gwsh17p2kn2pi51zrxck9xjj";
   };
 
-  configureFlags = [ "--enable-cxx" ];
+  configureFlags = [ "--enable-cxx" "--enable-fat" ];
 
   meta = {
     inherit version;
@@ -19,8 +19,8 @@ stdenv.mkDerivation rec {
     license = lib.licenses.lgpl3Plus;
     maintainers = [lib.maintainers.raskin];
     platforms = lib.platforms.unix;
-    downloadPage = "http://mpir.org/downloads.html";
-    homepage = "http://mpir.org/";
+    downloadPage = "https://mpir.org/downloads.html";
+    homepage = "https://mpir.org/";
     updateWalker = true;
   };
 }