diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 03e98869a..8e4a51874 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -26,6 +26,7 @@ node dependencies:
     - install -m 0644 .gitlab-ci/nix-bootstrap.conf /etc/nix/nix.conf
     - .gitlab-ci/write-minio-creds.sh
     - .gitlab-ci/make-minio-bucket.sh
+    - nix-env -f .gitlab-ci/patched-nix.nix -iE 'f: f {}'
     - cp -pr --reflink=auto -L .gitlab-ci/upload-to-cache.sh /etc/nix/upload-to-cache.sh
     - install -m 0644 .gitlab-ci/nix.conf /etc/nix/nix.conf
     - git config --global init.defaultBranch master
diff --git a/.gitlab-ci/debug-aws.patch b/.gitlab-ci/debug-aws.patch
new file mode 100644
index 000000000..a7583c295
--- /dev/null
+++ b/.gitlab-ci/debug-aws.patch
@@ -0,0 +1,12 @@
+diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
+index 6bfbee044..ff406e5e4 100644
+--- a/src/libstore/s3-binary-cache-store.cc
++++ b/src/libstore/s3-binary-cache-store.cc
+@@ -126,6 +126,7 @@ ref<Aws::Client::ClientConfiguration> S3Helper::makeConfig(const string & region
+     initAWS();
+     auto res = make_ref<Aws::Client::ClientConfiguration>();
+     res->region = region;
++    debug("configuring scheme %s", scheme);
+     if (!scheme.empty()) {
+         res->scheme = Aws::Http::SchemeMapper::FromString(scheme.c_str());
+     }
diff --git a/.gitlab-ci/nix.conf b/.gitlab-ci/nix.conf
index 713c109a0..29c91aba8 100644
--- a/.gitlab-ci/nix.conf
+++ b/.gitlab-ci/nix.conf
@@ -1,6 +1,6 @@
 sandbox = true
 experimental-features = nix-command flakes ca-references
-substituters = https://hydra.iohk.io https://cache.nixos.org/
+substituters = https://hydra.iohk.io https://cache.nixos.org/ s3://nix-cache?scheme=http&endpoint=minio-gitlab-runner-cache
 trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= minio-gitlab-runner-cache:ZN5neq93MHqpnieHSBlxGgWvCL0WKrZ2S9QS+U5Bnro=
 require-sigs = true
 post-build-hook = /etc/nix/upload-to-cache.sh
\ No newline at end of file
diff --git a/.gitlab-ci/patched-nix.nix b/.gitlab-ci/patched-nix.nix
new file mode 100644
index 000000000..7b5f707af
--- /dev/null
+++ b/.gitlab-ci/patched-nix.nix
@@ -0,0 +1,4 @@
+{ pkgs ? import <nixpkgs> {} }:
+pkgs.nixUnstable.overrideAttrs (oldAttrs: {
+  patches = oldAttrs.patches or [] ++ [ ./debug-aws.patch ];
+})
diff --git a/.gitlab-ci/upload-to-cache.sh b/.gitlab-ci/upload-to-cache.sh
index 171a4f00f..5adbd5cb8 100755
--- a/.gitlab-ci/upload-to-cache.sh
+++ b/.gitlab-ci/upload-to-cache.sh
@@ -5,4 +5,4 @@ set -f # disable globbing
 export IFS=' '
 
 echo "Signing and uploading paths" $OUT_PATHS
-exec nix --debug copy --to "s3://nix-cache?region=us-east-1&scheme=http&endpoint=minio-gitlab-runner-cache:80&secret-key=${NIX_CACHE_KEYFILE}" $OUT_PATHS
+exec nix --debug copy --to "s3://nix-cache?region=us-east-1&scheme=http&endpoint=minio-gitlab-runner-cache&secret-key=${NIX_CACHE_KEYFILE}" $OUT_PATHS