diff --git a/nix/ci.nix b/nix/ci.nix
index fa189273..6a6c296b 100644
--- a/nix/ci.nix
+++ b/nix/ci.nix
@@ -30,6 +30,9 @@
     # The `test` job ran the dev/test profiles, not crane's default release:
     # debug assertions and overflow checks are part of what it tested.
     CARGO_PROFILE = "";
+    # No DWARF in the dev/test artifacts: it was about half of the test build's
+    # disk and the runners hit ENOSPC linking it. Asserts are unaffected.
+    CARGO_PROFILE_DEV_DEBUG = "0";
   };
 
   wasmTarget = "wasm32-unknown-unknown";
@@ -103,6 +106,8 @@ in rec {
       // {
         pname = "improvise-test";
         cargoArtifacts = nativeDeps;
+        # Nothing reuses the test target dir; archiving it is more disk.
+        doInstallCargoArtifacts = false;
         cargoTestExtraArgs = "--workspace";
         nativeBuildInputs = [pkgs.python3 pkgs.git];
         # tests/shipped_documents_load.rs walks the git index (`git ls-files`)