diff --git a/maintainers/flake-module.nix b/maintainers/flake-module.nix
index a2edadebb..dd7d1d338 100644
--- a/maintainers/flake-module.nix
+++ b/maintainers/flake-module.nix
@@ -106,7 +106,6 @@
             enable = true;
             excludes = [
               # We haven't linted these files yet
-              ''^tests/functional/gc-concurrent2\.builder\.sh$''
               ''^tests/functional/gc-non-blocking\.sh$''
               ''^tests/functional/hash-convert\.sh$''
               ''^tests/functional/impure-derivations\.sh$''
diff --git a/tests/functional/gc-concurrent2.builder.sh b/tests/functional/gc-concurrent2.builder.sh
index 4f6c58b96..4b1ad6f5e 100644
--- a/tests/functional/gc-concurrent2.builder.sh
+++ b/tests/functional/gc-concurrent2.builder.sh
@@ -1,5 +1,8 @@
-mkdir $out
-echo $(cat $input1/foo)$(cat $input2/bar)xyzzy > $out/foobar
+# shellcheck shell=bash
+# shellcheck disable=SC2154
+mkdir "$out"
+# shellcheck disable=SC2154
+echo "$(cat "$input1"/foo)""$(cat "$input2"/bar)"xyzzy > "$out"/foobar
 
 # Check that the GC hasn't deleted the lock on our output.
 test -e "$out.lock"