diff --git a/.circleci/config.yml b/.circleci/config.yml
index 5d00d0845..5fce6c718 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -67,6 +67,8 @@ jobs:
           name: run spec tests
           command: |
             test/create_test_db "postgres://circleci@localhost" postgrest_test stack test
+      - store_artifacts:
+          path: /tmp/postgrest
 
   # Publish a new release. This only runs when a release is tagged (see
   # workflow below).
@@ -111,6 +113,8 @@ jobs:
             then
               postgrest-release-dockerhub-description
             fi
+      - store_artifacts:
+          path: /tmp/postgrest
 
   # Build everything in default.nix and push to the Cachix binary cache if running on main
   nix-build:
@@ -154,6 +158,8 @@ jobs:
               echo "Building all derivations (caching skipped for outside pull requests)..."
               nix-build
             fi
+      - store_artifacts:
+          path: /tmp/postgrest
 
   # Run tests
   nix-test:
@@ -218,7 +224,8 @@ jobs:
           name: Run memory tests
           command: postgrest-test-memory
           when: always
-
+      - store_artifacts:
+          path: /tmp/postgrest
 
 workflows:
   version: 2
diff --git a/nix/overlays/checked-shell-script/checked-shell-script.nix b/nix/overlays/checked-shell-script/checked-shell-script.nix
index 5deb12749..ae0af139c 100644
--- a/nix/overlays/checked-shell-script/checked-shell-script.nix
+++ b/nix/overlays/checked-shell-script/checked-shell-script.nix
@@ -3,6 +3,7 @@
 # to be used in a path for example.
 { argbash
 , bash_5
+, coreutils
 , git
 , lib
 , runCommand
@@ -83,7 +84,7 @@ let
 
         + lib.optionalString redirectTixFiles ''
           # storing tix files in a temporary throw away directory avoids mix/tix conflicts after changes
-          hpctixdir=$(mktemp -d)
+          hpctixdir=$(${coreutils}/bin/mktemp -d)
           export HPCTIXFILE="$hpctixdir"/postgrest.tix
           trap 'rm -rf $hpctixdir' EXIT
         ''
@@ -99,7 +100,8 @@ let
         ''
 
         + lib.optionalString withTmpDir ''
-          tmpdir="$(mktemp -d)"
+          mkdir -p "''${TMPDIR:-/tmp}/postgrest"
+          tmpdir="$(${coreutils}/bin/mktemp -d --tmpdir postgrest/${name}-XXX)"
 
           # we keep the tmpdir when an error occurs for debugging
           trap 'echo Temporary directory kept at: $tmpdir' ERR
diff --git a/nix/tools/withTools.nix b/nix/tools/withTools.nix
index ea9085d37..c74ce3224 100644
--- a/nix/tools/withTools.nix
+++ b/nix/tools/withTools.nix
@@ -41,6 +41,8 @@ let
         }
 
         mkdir -p "$tmpdir"/{db,socket}
+        # remove data dir, even if we keep tmpdir - no need to upload it to artifacts
+        trap 'rm -rf $tmpdir/db' EXIT
 
         export PGDATA="$tmpdir/db"
         export PGHOST="$tmpdir/socket"