diff --git a/overlay.nix b/overlay.nix
index a43e8940..578526a5 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -1,9 +1,10 @@
 final: /* Future last stage */
 prev:  /* Previous stage */
 
-with final.lib;
+#with final.lib;
 
 let
+  lib = prev.lib;
   callPackage = final.callPackage;
 
   bscPkgs = {
@@ -96,15 +97,18 @@ let
     };
   };
 
+  # Load our custom lib functions with import, callPackage fails.
+  lib' = import ./pkgs/lib.nix { lib = prev.lib; };
+
   # For now, only build toplevel packages in CI/Hydra
-  pkgsTopLevel = filterAttrs (_: isDerivation) bscPkgs;
+  pkgsTopLevel = lib.filterAttrs (_: lib.isDerivation) bscPkgs;
 
   # Native build in that platform doesn't imply cross build works
   canCrossCompile = platform: pkg:
-    (isDerivation pkg) &&
+    (lib.isDerivation pkg) &&
     # Must be defined explicitly
     (pkg.meta.cross or false) &&
-    (meta.availableOn platform pkg);
+    (lib.meta.availableOn platform pkg);
 
   # For now only RISC-V
   crossSet = { riscv64 = final.pkgsCross.riscv64.bsc.pkgsTopLevel; };
@@ -122,21 +126,17 @@ let
     '';
 
   pkgsList = buildList "ci-pkgs" (builtins.attrValues pkgsTopLevel);
-  testsList = buildList "ci-tests" (collect isDerivation tests);
+  testsList = buildList "ci-tests" (lib.collect lib.isDerivation tests);
   allList = buildList' "ci-all" [ pkgsList testsList ];
   # For now only RISC-V
   crossList = buildList "ci-cross"
-    (filter
+    (lib.filter
       (canCrossCompile final.pkgsCross.riscv64.stdenv.hostPlatform)
         (builtins.attrValues crossSet.riscv64));
 
 in bscPkgs // {
 
-  lib = prev.lib // {
-    maintainers = prev.lib.maintainers // {
-      bsc = import ./pkgs/maintainers.nix;
-    };
-  };
+  lib = lib';
 
   # Prevent accidental usage of bsc-ci attribute
   bsc-ci = throw "the bsc-ci attribute is deprecated, use bsc.ci";
diff --git a/pkgs/bench6/default.nix b/pkgs/bench6/default.nix
index 93ad8113..2dcf0e1a 100644
--- a/pkgs/bench6/default.nix
+++ b/pkgs/bench6/default.nix
@@ -14,16 +14,19 @@
 , openblas
 , ovni
 , gitBranch ? "master"
-, gitURL ? "ssh://git@bscpm04.bsc.es/rarias/bench6.git"
 , gitCommit ? "bf29a53113737c3aa74d2fe3d55f59868faea7b4"
+, gitUrls ? [
+  "ssh://git@bscpm04.bsc.es/rarias/bench6.git"
+  "https://github.com/rodarima/bench6.git"
+]
 }:
 
 stdenv.mkDerivation rec {
   pname = "bench6";
   version = "${src.shortRev}";
 
-  src = builtins.fetchGit {
-    url = gitURL;
+  src = lib.fetchGitMirror {
+    urls = gitUrls;
     ref = gitBranch;
     rev = gitCommit;
   };
diff --git a/pkgs/lib.nix b/pkgs/lib.nix
new file mode 100644
index 00000000..97cbe978
--- /dev/null
+++ b/pkgs/lib.nix
@@ -0,0 +1,30 @@
+{ lib }:
+
+let
+  # If not supported, fall back to tryEval, which will fail in the first case.
+  safeCatchAll = if (builtins ? catchAll)
+    then builtins.catchAll
+    else e: (builtins.tryEval e) // { msg = ""; };
+in lib.extend (_: lib: {
+  # Same as fetchGit but accepts a list of mirror urls
+  fetchGitMirror = { urls, ... } @ args:
+  let
+    cleanArgs = lib.removeAttrs args [ "urls" ];
+    fetchUrl = url: builtins.fetchGit (cleanArgs // { inherit url; });
+    safeFetch = url: safeCatchAll (fetchUrl url);
+    complain = url:
+    let
+      r = safeFetch url;
+    in
+      if (r.success) then r
+      else lib.warn "cannot fetch ${url}, trying next
+      mirror:${builtins.replaceStrings ["\n" ] ["\n> "] ("\n"+r.msg)}" r;
+    fetchList = lib.map (url: complain url) urls;
+    bad = throw "cannot fetch from any mirror";
+    good = lib.findFirst (e: e.success) bad fetchList;
+  in good.value;
+
+  maintainers = lib.maintainers // {
+    bsc = import ./maintainers.nix;
+  };
+})